Fluid Attacks Database

Description

pypdf: Possible large memory usage for large /ToUnicode streams (Follow-up 2)

Impact

An attacker who uses this vulnerability can craft a PDF which leads to large memory consumption. This requires parsing the /ToUnicode entry of a font with unusually large values, for example during text extraction.

Patches

This has been fixed in pypdf==6.18.1.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #4071.

Mitigation

Update Impact

Minimal update. May introduce new vulnerabilities or breaking changes.

Ecosystem	Component	Affected version	Patched versions
pypi	pypdf	>=0 <6.18.1	6.18.1
debian 12	pypdf	=3.17.4-1 \|\| =3.4.1-1 \|\| =3.4.1-1+deb12u1 \|\| =4.0.0-1 \|\| =4.0.0-1~exp1 \|\| =4.0.1-1 \|\| =4.0.2-1 \|\| =4.1.0-1 \|\| =4.2.0-1 \|\| =4.3.1-1 \|\| =5.4.0-1 \|\| =6.19.0-1 \|\| =6.9.0-1 \|\| =6.9.2-1 \|\| =6.9.2-2	-
debian 12	pypdf2	=2.12.1-3 \|\| =2.12.1-3+deb12u1 \|\| =2.12.1-4	-
debian 13	pypdf	=5.4.0-1 \|\| =6.19.0-1 \|\| =6.9.0-1 \|\| =6.9.2-1 \|\| =6.9.2-2	-
debian 14	pypdf	=5.4.0-1 \|\| =6.9.0-1 \|\| =6.9.2-1 \|\| =6.9.2-2 \|\| >=0 <6.19.0-1	6.19.0-1

Aliases

1. CVE-2026-1029952. NVD-2026-1029953. OSV-2026-1029954. OSV-DEBIAN-2026-1029955. GHSA-fp3h-c4fm-7vvf6. GCVE-2026-1029957. SECURITY-TRACKER-CVE-2026-102995

References

1. https://github.com/py-pdf/pypdf/security/advisories/GHSA-fp3h-c4fm-7vvf2. https://github.com/py-pdf/pypdf/pull/40713. https://github.com/py-pdf/pypdf/commit/319d0b823ce2c311a2435e9fd93c13994d32bb514. https://github.com/py-pdf/pypdf/releases/tag/6.18.1

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