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CVE-2026-102995: pypdf: Possible large memory usage for large /ToUnicode streams (Follow-up 2)

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-30 · updated 2026-10-05
• Weakness: CWE-400

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF can place unusually large source-code or destination-string tokens in a font /ToUnicode mapping, causing pypdf/_cmap.py parse_bfchar to decode and retain oversized values during operations such as text extraction and consume excessive memory. This is a second follow-up to earlier /ToUnicode resource-consumption fixes and is limited to the remaining token-length path. This issue is fixed in version 6.18.1.

Affected products

• py-pdf pypdf: before 6.18.1 — fixed in 6.18.1

How to fix

Upgrade to a fixed version: py-pdf pypdf 6.18.1. Check the vendor advisory for mitigations.

References

• https://github.com/py-pdf/pypdf/commit/319d0b823ce2c311a2435e9fd93c13994d32bb51
• https://github.com/py-pdf/pypdf/pull/4071
• https://github.com/py-pdf/pypdf/releases/tag/6.18.1
• https://github.com/py-pdf/pypdf/security/advisories/GHSA-fp3h-c4fm-7vvf

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