Common Weakness Enumeration

CWE-835

Allowed

Loop with Unreachable Exit Condition ('Infinite Loop')

Abstraction: Base · Status: Incomplete

API response cwe.mitre.org

The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

1253 vulnerabilities reference this CWE, most recent first.

GHSA-JJ3X-WXRX-4X23

Vulnerability from github – Published: 2026-01-05 23:10 – Updated: 2026-01-06 16:06
VLAI
Summary
AIOHTTP vulnerable to DoS when bypassing asserts
Details

Summary

When assert statements are bypassed, an infinite loop can occur, resulting in a DoS attack when processing a POST body.

Impact

If optimisations are enabled (-O or PYTHONOPTIMIZE=1), and the application includes a handler that uses the Request.post() method, then an attacker may be able to execute a DoS attack with a specially crafted message.

Patch: https://github.com/aio-libs/aiohttp/commit/bc1319ec3cbff9438a758951a30907b072561259

Severity
6.6 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.13.2"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "aiohttp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.13.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-69227"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-05T23:10:15Z",
    "nvd_published_at": "2026-01-06T00:15:48Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\nWhen assert statements are bypassed, an infinite loop can occur, resulting in a DoS attack when processing a POST body.\n\n### Impact\nIf optimisations are enabled (`-O` or `PYTHONOPTIMIZE=1`), and the application includes a handler that uses the `Request.post()` method, then an attacker may be able to execute a DoS attack with a specially crafted message.\n\n------\n\nPatch: https://github.com/aio-libs/aiohttp/commit/bc1319ec3cbff9438a758951a30907b072561259",
  "id": "GHSA-jj3x-wxrx-4x23",
  "modified": "2026-01-06T16:06:51Z",
  "published": "2026-01-05T23:10:15Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/aio-libs/aiohttp/security/advisories/GHSA-jj3x-wxrx-4x23"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-69227"
    },
    {
      "type": "WEB",
      "url": "https://github.com/aio-libs/aiohttp/commit/bc1319ec3cbff9438a758951a30907b072561259"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/aio-libs/aiohttp"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U",
      "type": "CVSS_V4"
    }
  ],
  "summary": "AIOHTTP vulnerable to DoS when bypassing asserts"
}

GHSA-JMPW-6QM3-5H67

Vulnerability from github – Published: 2026-10-08 18:32 – Updated: 2026-10-08 18:32
VLAI
Details

FFmpeg through 9.0.2 contains an infinite loop vulnerability in ff_rtsp_connect() in libavformat/rtsp.c that follows RTSP 3xx redirects without any redirect limit. Attackers controlling an RTSP server can answer every request with a 302 redirect to itself or another server, causing endless reconnects that saturate a CPU core.

Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
7.1 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2026-107696"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-08T18:17:26Z",
    "severity": "HIGH"
  },
  "details": "FFmpeg through 9.0.2 contains an infinite loop vulnerability in ff_rtsp_connect() in libavformat/rtsp.c that follows RTSP 3xx redirects without any redirect limit. Attackers controlling an RTSP server can answer every request with a 302 redirect to itself or another server, causing endless reconnects that saturate a CPU core.",
  "id": "GHSA-jmpw-6qm3-5h67",
  "modified": "2026-10-08T18:32:30Z",
  "published": "2026-10-08T18:32:30Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-107696"
    },
    {
      "type": "WEB",
      "url": "https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24902"
    },
    {
      "type": "WEB",
      "url": "https://gist.github.com/OxBat/648a0bd60c898f2ffb418e131ce26013"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FFmpeg/FFmpeg"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavformat/rtsp.c#L2225"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-infinite-loop-via-rtsp-redirect-handling-in-rtsp-c"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-JMWW-463H-74HC

Vulnerability from github – Published: 2022-05-24 16:49 – Updated: 2023-02-03 21:30
VLAI
Details

On BIG-IP 14.1.0-14.1.0.5 and 14.0.0-14.0.0.4, Malformed http requests made to an undisclosed iControl REST endpoint can lead to infinite loop of the restjavad process.

Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2019-6638"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2019-07-03T19:15:00Z",
    "severity": "MODERATE"
  },
  "details": "On BIG-IP 14.1.0-14.1.0.5 and 14.0.0-14.0.0.4, Malformed http requests made to an undisclosed iControl REST endpoint can lead to infinite loop of the restjavad process.",
  "id": "GHSA-jmww-463h-74hc",
  "modified": "2023-02-03T21:30:28Z",
  "published": "2022-05-24T16:49:25Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2019-6638"
    },
    {
      "type": "WEB",
      "url": "https://support.f5.com/csp/article/K67825238"
    },
    {
      "type": "WEB",
      "url": "https://support.f5.com/csp/article/K67825238?utm_source=f5support\u0026amp;utm_medium=RSS"
    },
    {
      "type": "WEB",
      "url": "http://www.securityfocus.com/bid/109106"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-JP53-MHQP-8XCG

Vulnerability from github – Published: 2026-09-01 21:20 – Updated: 2026-09-01 21:20
VLAI
Summary
pypdf: Possible infinite loop for TreeObject.insert_child
Details

Impact

An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires a (usually writing) code path where TreeObject.insert_child is involved.

Patches

This has been fixed in pypdf==6.16.0.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #3964.

Severity
6.9 (Medium)
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "pypdf"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.16.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-84309"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-01T21:20:20Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nAn attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires a (usually writing) code path where `TreeObject.insert_child` is involved.\n\n### Patches\n\nThis has been fixed in [pypdf==6.16.0](https://github.com/py-pdf/pypdf/releases/tag/6.16.0).\n\n### Workarounds\n\nIf you cannot upgrade yet, consider applying the changes from PR [#3964](https://github.com/py-pdf/pypdf/pull/3964).",
  "id": "GHSA-jp53-mhqp-8xcg",
  "modified": "2026-09-01T21:20:20Z",
  "published": "2026-09-01T21:20:20Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/security/advisories/GHSA-jp53-mhqp-8xcg"
    },
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/pull/3964"
    },
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/commit/c9ba557d565d57c53a0b3a0be06c0a4c29b0559b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/py-pdf/pypdf"
    },
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/releases/tag/6.16.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "pypdf: Possible infinite loop for TreeObject.insert_child"
}

GHSA-JP6G-7MQJ-WJ53

Vulnerability from github – Published: 2026-07-21 15:30 – Updated: 2026-08-19 06:31
VLAI
Details

A flaw was found in libssh. Logic errors in automatic certificate-based public key authentication can cause libssh clients to loop indefinitely when configured certificates are missing or repeatedly rejected by a server, leading to denial of service.

Severity
3.1 (Low)
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2026-59849"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-21T15:16:37Z",
    "severity": "LOW"
  },
  "details": "A flaw was found in libssh. Logic errors in automatic certificate-based public key authentication can cause libssh clients to loop indefinitely when configured certificates are missing or repeatedly rejected by a server, leading to denial of service.",
  "id": "GHSA-jp6g-7mqj-wj53",
  "modified": "2026-08-19T06:31:16Z",
  "published": "2026-07-21T15:30:44Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59849"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/errata/RHSA-2026:42922"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/errata/RHSA-2026:55855"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/security/cve/CVE-2026-59849"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2498182"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-JPJM-C3R5-Q96R

Vulnerability from github – Published: 2026-07-21 21:32 – Updated: 2026-07-23 15:30
VLAI
Details

A norm.Iter can enter an infinite loop when handling input containing invalid UTF-8 bytes.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2026-56852"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-21T20:17:02Z",
    "severity": "HIGH"
  },
  "details": "A norm.Iter can enter an infinite loop when handling input containing invalid UTF-8 bytes.",
  "id": "GHSA-jpjm-c3r5-q96r",
  "modified": "2026-07-23T15:30:35Z",
  "published": "2026-07-21T21:32:40Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-56852"
    },
    {
      "type": "WEB",
      "url": "https://go.dev/cl/794100"
    },
    {
      "type": "WEB",
      "url": "https://go.dev/issue/80142"
    },
    {
      "type": "WEB",
      "url": "https://pkg.go.dev/vuln/GO-2026-5970"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-JPQ9-R35R-969Q

Vulnerability from github – Published: 2022-05-24 19:04 – Updated: 2022-05-24 19:04
VLAI
Details

Infinite loop in DVB-S2-BB dissector in Wireshark 3.4.0 to 3.4.5 allows denial of service via packet injection or crafted capture file

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2021-22222"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2021-06-07T13:15:00Z",
    "severity": "HIGH"
  },
  "details": "Infinite loop in DVB-S2-BB dissector in Wireshark 3.4.0 to 3.4.5 allows denial of service via packet injection or crafted capture file",
  "id": "GHSA-jpq9-r35r-969q",
  "modified": "2022-05-24T19:04:14Z",
  "published": "2022-05-24T19:04:14Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-22222"
    },
    {
      "type": "WEB",
      "url": "https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-22222.json"
    },
    {
      "type": "WEB",
      "url": "https://gitlab.com/wireshark/wireshark/-/merge_requests/3130"
    },
    {
      "type": "WEB",
      "url": "https://security.gentoo.org/glsa/202107-21"
    },
    {
      "type": "WEB",
      "url": "https://www.debian.org/security/2021/dsa-5019"
    },
    {
      "type": "WEB",
      "url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
    },
    {
      "type": "WEB",
      "url": "https://www.wireshark.org/security/wnpa-sec-2021-05.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-JQ6P-6WG4-WRW8

Vulnerability from github – Published: 2024-07-23 15:31 – Updated: 2024-07-25 18:32
VLAI
Details

go-chart v2.1.1 was discovered to contain an infinite loop via the drawCanvas() function.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2024-40060"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-07-23T15:15:04Z",
    "severity": "HIGH"
  },
  "details": "go-chart v2.1.1 was discovered to contain an infinite loop via the drawCanvas() function.",
  "id": "GHSA-jq6p-6wg4-wrw8",
  "modified": "2024-07-25T18:32:35Z",
  "published": "2024-07-23T15:31:09Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-40060"
    },
    {
      "type": "WEB",
      "url": "https://gist.github.com/F3iG0n9/4d0d7c863eea6874eeeb26a3073aa5f8"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-JQ6W-JF5J-5585

Vulnerability from github – Published: 2022-05-13 01:47 – Updated: 2022-05-13 01:47
VLAI
Details

crypto/ahash.c in the Linux kernel through 4.10.9 allows attackers to cause a denial of service (API operation calling its own callback, and infinite recursion) by triggering EBUSY on a full queue.

Severity
7.5 (High)
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2017-7618"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2017-04-10T14:59:00Z",
    "severity": "HIGH"
  },
  "details": "crypto/ahash.c in the Linux kernel through 4.10.9 allows attackers to cause a denial of service (API operation calling its own callback, and infinite recursion) by triggering EBUSY on a full queue.",
  "id": "GHSA-jq6w-jf5j-5585",
  "modified": "2022-05-13T01:47:03Z",
  "published": "2022-05-13T01:47:03Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2017-7618"
    },
    {
      "type": "WEB",
      "url": "https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US\u0026docId=emr_na-hpesbhf03800en_us"
    },
    {
      "type": "WEB",
      "url": "http://marc.info/?l=linux-crypto-vger\u0026m=149181655623850\u0026w=2"
    },
    {
      "type": "WEB",
      "url": "http://www.securityfocus.com/bid/97534"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-JQHH-CJMQ-VMV6

Vulnerability from github – Published: 2026-09-09 23:53 – Updated: 2026-09-09 23:53
VLAI
Summary
Open WebUI: Any authenticated user can hang the server via a cyclic chat message history
Details

Summary

Chat histories are stored as an unvalidated JSON object. The walk that reconstructs a chat's message chain detected repeats using each message's own id field while moving through the history by map key, so a message that simply omitted id was never recorded as visited. A history whose messages referenced each other in a parent cycle therefore made the walk run forever. Any account with the default user role could store such a chat and trigger the walk, blocking the server for everyone.

Preconditions

One account with the default user role. No administrator rights, no additional permissions, no configuration change and no non-default setting: creating a chat is available to every user out of the box. The attack runs entirely against the attacker's own chat, so no knowledge of any other user's data is needed. Instances where every account is trusted are affected in the sense that the fault is reachable, but require a user acting deliberately.

Impact

The walk is synchronous and runs on the asyncio event loop, so while it spins, every request from every user is blocked, including unauthenticated /health and administrator endpoints. External health checks and orchestrator liveness probes fail alongside the UI. The list it appends to grows without bound, so a memory-capped deployment ends in an out-of-memory kill rather than a hang. The work is not cancelled when the client disconnects, so one fire-and-forget request is enough and the attacker can disconnect immediately. The malformed chat stays in the database, so restarting the process does not clear the condition: the next request that walks that chat hangs the new process, and recovery requires deleting the stored chat. No data is disclosed, altered or deleted.

Fix

Fixed in 0.11.1 by https://github.com/open-webui/open-webui/commit/5c79ccc9e5c9efc2bc024d8f0b9757652ece929a. The walk now records the map key it is currently positioned at instead of the message's self-reported id, so it terminates after at most one step per stored message whatever the message contents are. Upgrading fully resolves the issue, including for chats stored while the deployment was on an affected version, which become harmless once the walk terminates.

Root cause

Affected component: the message-chain reconstruction helper in backend/open_webui/utils/misc.py, reached from every path that rebuilds a chat's history, including chat completion, per-chat statistics, context compaction, subagents and timers. Affected setup: all builds from 0.5.0 up to and including 0.11.0.

The loop's visited set was keyed on the message body's id field while the loop itself advanced by looking the parent up as a key in the history map, so the two used different notions of identity. That id field is part of the stored chat object and is fully attacker-controlled, and the guard explicitly skipped recording it when absent, which left the exit condition unreachable for any message that omitted it. The write path does not validate the structure of a chat's history, so a history containing id-less messages in a parent cycle was persisted exactly as submitted.

Proof of concept

As a default-role user on a running instance, store one chat of two messages that reference each other as parents, with the id field omitted:

{"chat":{"title":"poc","history":{"currentId":"A","messages":{
  "A":{"parentId":"B","role":"user","content":"a","childrenIds":[]},
  "B":{"parentId":"A","role":"assistant","content":"b","childrenIds":[]}}}}}

POST /api/v1/chats/new stores it verbatim. A single subsequent GET /api/v1/chats/stats/usage as the same user then never returns. Sampled during the hang, the worker consumed one full CPU core and reached 1.86 GB resident within 60 seconds, still growing. Unauthenticated GET /health and administrator API calls both time out for as long as the process lives, and continue to do so after the attacker's connection closes. Restarting the server restores service until the first request that walks the stored chat, which hangs the new process the same way.

On 0.11.1 the same payload returns promptly, /health stays available throughout, and a well-formed chat still resolves its full history.

Credits

@YashvantHange, who reported the missing-id cycle in the message-chain walk, demonstrated the resulting server-wide outage end to end against a live instance, and showed that it survives both attacker disconnect and a process restart.

Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "open-webui"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.5.0"
            },
            {
              "fixed": "0.11.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-88002"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-09T23:53:59Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\nChat histories are stored as an unvalidated JSON object. The walk that reconstructs a chat\u0027s message chain detected repeats using each message\u0027s own `id` field while moving through the history by map key, so a message that simply omitted `id` was never recorded as visited. A history whose messages referenced each other in a parent cycle therefore made the walk run forever. Any account with the default `user` role could store such a chat and trigger the walk, blocking the server for everyone.\n\n## Preconditions\nOne account with the default `user` role. No administrator rights, no additional permissions, no configuration change and no non-default setting: creating a chat is available to every user out of the box. The attack runs entirely against the attacker\u0027s own chat, so no knowledge of any other user\u0027s data is needed. Instances where every account is trusted are affected in the sense that the fault is reachable, but require a user acting deliberately.\n\n## Impact\nThe walk is synchronous and runs on the asyncio event loop, so while it spins, every request from every user is blocked, including unauthenticated `/health` and administrator endpoints. External health checks and orchestrator liveness probes fail alongside the UI. The list it appends to grows without bound, so a memory-capped deployment ends in an out-of-memory kill rather than a hang. The work is not cancelled when the client disconnects, so one fire-and-forget request is enough and the attacker can disconnect immediately. The malformed chat stays in the database, so restarting the process does not clear the condition: the next request that walks that chat hangs the new process, and recovery requires deleting the stored chat. No data is disclosed, altered or deleted.\n\n## Fix\nFixed in 0.11.1 by https://github.com/open-webui/open-webui/commit/5c79ccc9e5c9efc2bc024d8f0b9757652ece929a. The walk now records the map key it is currently positioned at instead of the message\u0027s self-reported `id`, so it terminates after at most one step per stored message whatever the message contents are. Upgrading fully resolves the issue, including for chats stored while the deployment was on an affected version, which become harmless once the walk terminates.\n\n## Root cause\nAffected component: the message-chain reconstruction helper in `backend/open_webui/utils/misc.py`, reached from every path that rebuilds a chat\u0027s history, including chat completion, per-chat statistics, context compaction, subagents and timers. Affected setup: all builds from 0.5.0 up to and including 0.11.0.\n\nThe loop\u0027s visited set was keyed on the message body\u0027s `id` field while the loop itself advanced by looking the parent up as a key in the history map, so the two used different notions of identity. That `id` field is part of the stored chat object and is fully attacker-controlled, and the guard explicitly skipped recording it when absent, which left the exit condition unreachable for any message that omitted it. The write path does not validate the structure of a chat\u0027s history, so a history containing id-less messages in a parent cycle was persisted exactly as submitted.\n\n## Proof of concept\nAs a default-role user on a running instance, store one chat of two messages that reference each other as parents, with the `id` field omitted:\n\n```json\n{\"chat\":{\"title\":\"poc\",\"history\":{\"currentId\":\"A\",\"messages\":{\n  \"A\":{\"parentId\":\"B\",\"role\":\"user\",\"content\":\"a\",\"childrenIds\":[]},\n  \"B\":{\"parentId\":\"A\",\"role\":\"assistant\",\"content\":\"b\",\"childrenIds\":[]}}}}}\n```\n\n`POST /api/v1/chats/new` stores it verbatim. A single subsequent `GET /api/v1/chats/stats/usage` as the same user then never returns. Sampled during the hang, the worker consumed one full CPU core and reached 1.86 GB resident within 60 seconds, still growing. Unauthenticated `GET /health` and administrator API calls both time out for as long as the process lives, and continue to do so after the attacker\u0027s connection closes. Restarting the server restores service until the first request that walks the stored chat, which hangs the new process the same way.\n\nOn 0.11.1 the same payload returns promptly, `/health` stays available throughout, and a well-formed chat still resolves its full history.\n\n## Credits\n@YashvantHange, who reported the missing-`id` cycle in the message-chain walk, demonstrated the resulting server-wide outage end to end against a live instance, and showed that it survives both attacker disconnect and a process restart.",
  "id": "GHSA-jqhh-cjmq-vmv6",
  "modified": "2026-09-09T23:53:59Z",
  "published": "2026-09-09T23:53:59Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-jqhh-cjmq-vmv6"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/pull/28034"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/commit/5c79ccc9e5c9efc2bc024d8f0b9757652ece929a"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/open-webui/open-webui"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/releases/tag/v0.11.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Open WebUI: Any authenticated user can hang the server via a cyclic chat message history"
}

No mitigation information available for this CWE.

No CAPEC attack patterns related to this CWE.

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