GHSA-HQMH-PPP3-XVM7

Vulnerability from github – Published: 2026-03-11 00:14 – Updated: 2026-03-11 05:46
VLAI
Summary
pypdf: manipulated stream length values can exhaust RAM
Details

Impact

An attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing a content stream with a rather large /Length value, regardless of the actual data length inside the stream.

Patches

This has been fixed in pypdf==6.8.0.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #3675.

As far as we are aware, this mostly affects reading from buffers of unknown size, as returned by open("file.pdf", mode="rb") for example. Passing a file path or a BytesIO buffer to pypdf instead does not seem to trigger the vulnerability.

Severity
6.8 (Medium)
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "pypdf"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.8.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-31826"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-11T00:14:02Z",
    "nvd_published_at": "2026-03-10T22:16:20Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nAn attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing a content stream with a rather large `/Length` value, regardless of the actual data length inside the stream.\n\n### Patches\nThis has been fixed in [pypdf==6.8.0](https://github.com/py-pdf/pypdf/releases/tag/6.8.0).\n\n### Workarounds\nIf you cannot upgrade yet, consider applying the changes from PR [#3675](https://github.com/py-pdf/pypdf/pull/3675).\n\nAs far as we are aware, this mostly affects reading from buffers of unknown size, as returned by `open(\"file.pdf\", mode=\"rb\")` for example. Passing a file path or a `BytesIO` buffer to *pypdf* instead does not seem to trigger the vulnerability.",
  "id": "GHSA-hqmh-ppp3-xvm7",
  "modified": "2026-03-11T05:46:57Z",
  "published": "2026-03-11T00:14:02Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/security/advisories/GHSA-hqmh-ppp3-xvm7"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31826"
    },
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/pull/3675"
    },
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/commit/3c550b3196adeba1506a26e57c09c09fac75e9aa"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/py-pdf/pypdf"
    },
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/releases/tag/6.8.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "pypdf: manipulated stream length values can exhaust RAM"
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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  • 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.



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