All vulnerabilities
CVE-2026-102997GHSA-jw7q-gvrg-4vj3PYSEC-2026-4156

pypdf: Possible long runtimes for partially malformed FlateDecode streams (Follow-up)

py-pdf pypdfpipLibraries & packages
Open in ThreatlineRecord JSON
CVSS
8.7High
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.34%Chance of exploitation activity in the next 30 days, higher than 26% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in6.18.1Fixed versionGitHub
Published30 Sep 2026Updated 2 Oct 2026CVE List

What fixes it

  • 6.18.1pypdf, pipGitHub
  • 6.18.1pypdf, PyPIOSVpip install "pypdf>=6.18.1"

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

Impact

An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a partially malformed /FlateDecode stream, where the byte-by-byte decompression is used.

Patches

This has been fixed in pypdf==6.18.1.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #4073.

Text from GitHub Advisory Database

Affected versions 53

  • pypdf, pip< 6.18.1GitHub
  • pypdfaffected: < 6.18.1CVE List
  • pypdf, PyPIfrom first release, fixed in 6.18.1OSV
  • pypdf, PyPI1.0OSV
  • pypdf, PyPI1.1OSV
  • pypdf, PyPI1.10OSV
  • pypdf, PyPI1.11OSV
  • pypdf, PyPI1.12OSV
  • pypdf, PyPI1.13OSV
  • pypdf, PyPI1.2OSV
  • pypdf, PyPI1.3OSV
  • pypdf, PyPI1.4OSV
  • pypdf, PyPI1.5OSV
  • pypdf, PyPI1.6OSV
  • pypdf, PyPI1.7OSV
  • pypdf, PyPI1.8OSV
  • pypdf, PyPI1.9OSV
  • pypdf, PyPI3.1.0OSV
  • pypdf, PyPI3.10.0OSV
  • pypdf, PyPI3.11.0OSV
  • pypdf, PyPI3.11.1OSV
  • pypdf, PyPI3.12.0OSV
  • pypdf, PyPI3.12.1OSV
  • pypdf, PyPI3.12.2OSV
  • pypdf, PyPI3.13.0OSV
  • pypdf, PyPI3.14.0OSV
  • pypdf, PyPI3.15.0OSV
  • pypdf, PyPI3.15.1OSV
  • pypdf, PyPI3.15.2OSV
  • pypdf, PyPI3.15.3OSV
  • pypdf, PyPI3.15.4OSV
  • pypdf, PyPI3.15.5OSV
  • pypdf, PyPI3.16.0OSV
  • pypdf, PyPI3.16.1OSV
  • pypdf, PyPI3.16.2OSV
  • pypdf, PyPI3.16.3OSV
  • pypdf, PyPI3.16.4OSV
  • pypdf, PyPI3.17.0OSV
  • pypdf, PyPI3.17.1OSV
  • pypdf, PyPI3.17.2OSV
  • pypdf, PyPI3.17.3OSV
  • pypdf, PyPI3.17.4OSV
  • pypdf, PyPI3.2.0OSV
  • pypdf, PyPI3.2.1OSV
  • pypdf, PyPI3.3.0OSV
  • pypdf, PyPI3.4.0OSV
  • pypdf, PyPI3.4.1OSV
  • pypdf, PyPI3.5.0OSV
  • pypdf, PyPI3.5.1OSV
  • pypdf, PyPI3.5.2OSV
  • pypdf, PyPI3.6.0OSV
  • pypdf, PyPI3.7.0OSV
  • pypdf, PyPI3.7.1OSV

References 6