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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.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.