What’s Vulnerable › Vulnerabilities

CVE-2026-41312: pypdf: Manipulated FlateDecode predictor parameters can exhaust RAM

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-22 · updated 2026-06-17
• Weakness: CWE-789

Description

pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions prior to 6.10.2 can craft a PDF which leads to the RAM being exhausted. This requires accessing a stream compressed using `/FlateDecode` with a `/Predictor` unequal 1 and large predictor parameters. This has been fixed in pypdf 6.10.2. As a workaround, one may apply the changes from the patch manually.

Affected products

• py-pdf pypdf: before 6.10.2 — fixed in 6.10.2

How to fix

Upgrade to a fixed version: py-pdf pypdf 6.10.2. Check the vendor advisory for mitigations.

References

• https://github.com/py-pdf/pypdf/commit/ac734dab4eef92bcce50d503949b4d9887d89f11
• https://github.com/py-pdf/pypdf/pull/3734
• https://github.com/py-pdf/pypdf/releases/tag/6.10.2
• https://github.com/py-pdf/pypdf/security/advisories/GHSA-7gw9-cf7v-778f

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