PYSEC-2026-1837

Vulnerability from pysec - Published: 2026-07-07 11:45 - Updated: 2026-07-07 17:25
VLAI
Details

Impact

An attacker who uses this vulnerability can craft a PDF which leads to unexpected long runtime. This quadratic runtime blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage.

Patches

https://github.com/py-pdf/pypdf/pull/808

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?

References

Severity
6.2 (Medium)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Impacted products
Name purl
pypdf2 pkg:pypi/pypdf2
Aliases
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "pypdf2",
        "purl": "pkg:pypi/pypdf2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.27.9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.15",
        "1.16",
        "1.17",
        "1.18",
        "1.19",
        "1.20",
        "1.21",
        "1.22",
        "1.23",
        "1.24",
        "1.25",
        "1.25.1",
        "1.26.0",
        "1.27.0",
        "1.27.1",
        "1.27.2",
        "1.27.3",
        "1.27.4",
        "1.27.5",
        "1.27.6",
        "1.27.7",
        "1.27.8"
      ]
    }
  ],
  "aliases": [
    "CVE-2023-36810",
    "GHSA-jrm6-h9cq-8gqw"
  ],
  "details": "### Impact\nAn attacker who uses this vulnerability can craft a PDF which leads to unexpected long runtime.\nThis quadratic runtime blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage.\n\n### Patches\nhttps://github.com/py-pdf/pypdf/pull/808\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\n\n### References\n* [PyPDF2 PR #808](https://github.com/py-pdf/pypdf/pull/808)\n* [PyPDF2 Issue #582](https://github.com/py-pdf/pypdf/issues/582)",
  "id": "PYSEC-2026-1837",
  "modified": "2026-07-07T17:25:13.325659Z",
  "published": "2026-07-07T11:45:19.715500Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/security/advisories/GHSA-jrm6-h9cq-8gqw"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-36810"
    },
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/issues/582"
    },
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/pull/808"
    },
    {
      "type": "FIX",
      "url": "https://github.com/py-pdf/pypdf/commit/c6c56f550bb384e05f0139c796ba1308837d6373"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/py-pdf/pypdf"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2023/07/msg00019.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/pypdf2"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-jrm6-h9cq-8gqw"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "PyPDF2 quadratic runtime with malformed PDF missing xref marker"
}



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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

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.


Detection rules are retrieved from Rulezet.