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EUVD-2026-364861

European Vulnerability Database identifier assigned by ENISA

Reserved

2026-10-02 08:34

Assigner

ENISA

Alias of

a CVE record, shown under related vulnerabilities. This identifier carries no description, severity or references of its own: they belong to that CVE.

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{
  "assigner": "ENISA",
  "date_reserved": "2026-10-02T08:34:46.136323+00:00",
  "id": "EUVD-2026-364861"
}

CVE-2026-64422 (GCVE-0-2026-64422)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:51 – Updated: 2026-09-08 08:50

Title

net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes

Summary

In the Linux kernel, the following vulnerability has been resolved: net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes Reject invalid `net.ipv4.tcp_reordering` values before they reach TCP socket state. The sysctl is stored as an `int` but copied into the `u32` `tp->reordering` field for new sockets, so negative writes wrap to large values. With `tcp_mtu_probing=2`, the wrapped value can overflow the `tcp_mtu_probe()` size calculation and drive the MTU probing path into an out-of-bounds read. Route `tcp_reordering` writes through `proc_dointvec_minmax()` and require it to be at least 1. Also require `tcp_max_reordering` to be at least 1 so the configured maximum cannot become negative either. When registering the table for a non-init network namespace, relocate `extra2` pointers that refer into `init_net.ipv4` so the `tcp_reordering` upper bound follows that namespace's `tcp_max_reordering`. Harden `tcp_mtu_probe()` itself by computing `size_needed` as `u64`. This keeps the send queue and window checks from being bypassed through signed integer overflow.

Severity

7.1 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Assigner

Linux mitre root Scorecard

References

9 references

URL	Tags
https://git.kernel.org/stable/c/f0d88a4cd03affff6…
https://git.kernel.org/stable/c/27ddf4486c7dbf5bd…
https://git.kernel.org/stable/c/782708ca1ea1f68b8…
https://git.kernel.org/stable/c/e81f805824a810950…
https://git.kernel.org/stable/c/99206ce2244f8a3ed…
https://git.kernel.org/stable/c/bbae351c0f32f7c20…
https://git.kernel.org/stable/c/a094ac95d3b69adfa…
https://git.kernel.org/stable/c/efb8763d7bbb40cff…
https://cert-portal.siemens.com/productcert/html/…

Impacted products

5 products

Vendor	Product	Version
Linux	Linux	Affected: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf , < f0d88a4cd03affff6c08adf6c63964e235aede43 (git) Affected: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf , < 27ddf4486c7dbf5bdd393fa8bef6b67179796d98 (git) Affected: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf , < 782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae (git) Affected: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf , < e81f805824a8109504fce090641b17d135b48cd1 (git) Affected: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf , < 99206ce2244f8a3ed64298d0667c9055845a5dc7 (git) Affected: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf , < bbae351c0f32f7c200249e4aa6561b2b419dcf69 (git) Affected: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf , < a094ac95d3b69adfa1676eb9c8eae6835d4f1671 (git) Affected: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf , < efb8763d7bbb40cff4cc55a6b62c3095a038149c (git)
Linux	Linux	Affected: 2.6.24 Unaffected: 0 , < 2.6.24 (semver) Unaffected: 5.10.261 , ≤ 5.10.* (semver) Unaffected: 5.15.212 , ≤ 5.15.* (semver) Unaffected: 6.1.178 , ≤ 6.1.* (semver) Unaffected: 6.6.145 , ≤ 6.6.* (semver) Unaffected: 6.12.96 , ≤ 6.12.* (semver) Unaffected: 6.18.39 , ≤ 6.18.* (semver) Unaffected: 7.1.4 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)
Siemens	SIMATIC S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.6 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP	Affected: V3.1.6 , < * (custom)
Siemens	SIPLUS S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.6 , < * (custom)

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "affected": [
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
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                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
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                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
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            ]
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          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
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                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
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          },
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            "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          },
          {
            "defaultStatus": "unknown",
            "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
            "vendor": "Siemens",
            "versions": [
              {
                "lessThan": "*",
                "status": "affected",
                "version": "V3.1.6",
                "versionType": "custom"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-08T08:50:37.174Z",
          "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
          "shortName": "siemens-SADP"
        },
        "references": [
          {
            "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
          }
        ],
        "x_adpType": "supplier"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/sysctl_net_ipv4.c",
            "net/ipv4/tcp_output.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f0d88a4cd03affff6c08adf6c63964e235aede43",
              "status": "affected",
              "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf",
              "versionType": "git"
            },
            {
              "lessThan": "27ddf4486c7dbf5bdd393fa8bef6b67179796d98",
              "status": "affected",
              "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf",
              "versionType": "git"
            },
            {
              "lessThan": "782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae",
              "status": "affected",
              "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf",
              "versionType": "git"
            },
            {
              "lessThan": "e81f805824a8109504fce090641b17d135b48cd1",
              "status": "affected",
              "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf",
              "versionType": "git"
            },
            {
              "lessThan": "99206ce2244f8a3ed64298d0667c9055845a5dc7",
              "status": "affected",
              "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf",
              "versionType": "git"
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            {
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              "status": "affected",
              "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf",
              "versionType": "git"
            },
            {
              "lessThan": "a094ac95d3b69adfa1676eb9c8eae6835d4f1671",
              "status": "affected",
              "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf",
              "versionType": "git"
            },
            {
              "lessThan": "efb8763d7bbb40cff4cc55a6b62c3095a038149c",
              "status": "affected",
              "version": "91cc17c0e5e5ada156a8d5787a2509d263ea6bbf",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/sysctl_net_ipv4.c",
            "net/ipv4/tcp_output.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.24"
            },
            {
              "lessThan": "2.6.24",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.261",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.212",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.96",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.261",
                  "versionStartIncluding": "2.6.24",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.212",
                  "versionStartIncluding": "2.6.24",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.178",
                  "versionStartIncluding": "2.6.24",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.96",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.39",
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv4: bound TCP reordering sysctl writes and MTU probe sizes\n\nReject invalid `net.ipv4.tcp_reordering` values before they reach TCP\nsocket state. The sysctl is stored as an `int` but copied into the\n`u32` `tp-\u003ereordering` field for new sockets, so negative writes wrap\nto large values.\n\nWith `tcp_mtu_probing=2`, the wrapped value can overflow the\n`tcp_mtu_probe()` size calculation and drive the MTU probing path into\nan out-of-bounds read. Route `tcp_reordering` writes through\n`proc_dointvec_minmax()` and require it to be at least 1. Also require\n`tcp_max_reordering` to be at least 1 so the configured maximum cannot\nbecome negative either.\n\nWhen registering the table for a non-init network namespace, relocate\n`extra2` pointers that refer into `init_net.ipv4` so the\n`tcp_reordering` upper bound follows that namespace\u0027s\n`tcp_max_reordering`.\n\nHarden `tcp_mtu_probe()` itself by computing `size_needed` as `u64`.\nThis keeps the send queue and window checks from being bypassed through\nsigned integer overflow."
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          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The attacker must locally write the per-network-namespace TCP sysctls and exercise a TCP socket; remote packets alone cannot introduce the invalid signed value.\nAC:L - The attacker can set both tcp_reordering and tcp_mtu_probing=2, establish an attacker-controlled TCP connection, grow its congestion window, and control queued data and receiver-window conditions.\nPR:L - Writes require CAP_NET_ADMIN in the network namespace\u2019s owning user namespace, which an unprivileged user can obtain by creating user and network namespaces on systems permitting unprivileged user namespaces.\nUI:N - The attacker can configure the namespace and trigger MTU probing using their own TCP endpoints without any victim action.\nS:U - The vulnerable TCP implementation and the affected kernel memory and availability remain within the Linux kernel\u2019s security authority.\nC:H - The overflow bypasses send-queue validation and causes an out-of-bounds kernel-memory read through an invalid skb traversal, potentially exposing sensitive kernel data.\nI:N - The established primitive is an out-of-bounds read and malformed skb state; the affected path provides no demonstrated out-of-bounds write or other data-modification primitive.\nA:H - The invalid skb access and inconsistent payload geometry can cause an OOPS, BUG, or kernel panic, and an attacker can trigger the path repeatedly."
            }
          ]
        }
      ],
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/efb8763d7bbb40cff4cc55a6b62c3095a038149c"
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      "title": "net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes",
      "x_generator": {
        "engine": "bippy-1.2.0"
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  },
  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64422",
    "datePublished": "2026-07-25T08:51:00.671Z",
    "dateReserved": "2026-07-19T15:36:31.787Z",
    "dateUpdated": "2026-09-08T08:50:37.174Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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EUVD-2026-364861

CVE-2026-64422 (GCVE-0-2026-64422)

Tags

Sightings

Nomenclature

Related by attack behaviour