GHSA-R73J-PQJ5-W3X7

Vulnerability from github – Published: 2026-05-04 20:19 – Updated: 2026-05-13 13:41
VLAI
Summary
Pillow has a PDF Parsing Trailer Infinite Loop (DoS)
Details

Impact

An attacker can supply a malicious PDF that causes the process to hang indefinitely, consuming 100% CPU and making the application unresponsive.

Patches

Patched version: 12.2.0.

PdfParser (introduced in Pillow 4.2.0) follows Prev pointers in PDF trailers to read cross-reference sections. If a trailer's Prev pointer references an offset that has already been processed — either pointing to itself or forming a longer cycle — the parser enters an infinite loop. Pillow now tracks previously processed trailer offsets and raises an error if a cycle is detected.

Workarounds

Use any version but the affected versions: >= 4.2.0, < 12.2.0

Resources

  • Fix: https://github.com/python-pillow/Pillow/pull/9519
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.1 (Medium)
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "pillow"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.2.0"
            },
            {
              "fixed": "12.2.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-42310"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-04T20:19:30Z",
    "nvd_published_at": "2026-05-09T06:16:10Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\nAn attacker can supply a malicious PDF that causes the process to hang indefinitely, consuming 100% CPU and making the application unresponsive.\n\n### Patches\nPatched version: 12.2.0.\n\nPdfParser (introduced in Pillow 4.2.0) follows Prev pointers in PDF trailers to read cross-reference sections. If a\ntrailer\u0027s Prev pointer references an offset that has already been processed \u2014 either pointing to itself or forming a\nlonger cycle \u2014 the parser enters an infinite loop. Pillow now tracks previously processed trailer offsets and raises an\nerror if a cycle is detected.\n\n### Workarounds\nUse any version but the affected versions: \u003e= 4.2.0, \u003c 12.2.0\n\n### Resources\n - Fix: https://github.com/python-pillow/Pillow/pull/9519",
  "id": "GHSA-r73j-pqj5-w3x7",
  "modified": "2026-05-13T13:41:22Z",
  "published": "2026-05-04T20:19:30Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/python-pillow/Pillow/security/advisories/GHSA-r73j-pqj5-w3x7"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42310"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python-pillow/Pillow/pull/9519"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python-pillow/Pillow/commit/3bf614e4b8615d0ce1d5039efaf6db447fe7c468"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/python-pillow/Pillow"
    },
    {
      "type": "WEB",
      "url": "https://github.com/python-pillow/Pillow/releases/tag/12.2.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Pillow has a PDF Parsing Trailer Infinite Loop (DoS)"
}



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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
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