What’s Vulnerable › Vulnerabilities

CVE-2026-102998: pypdf: Possible long runtimes when generating appearance streams

• 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 6.19.0, a crafted PDF with form field values can cause pypdf/generic/_appearance_stream.py appearance-stream generation to repeat invariant selection-data work inside a loop when an application updates fields with flattening enabled, resulting in excessive runtimes and application unavailability. This issue is fixed in version 6.19.0.

Affected products

• py-pdf pypdf: before 6.19.0 — fixed in 6.19.0

How to fix

Upgrade to a fixed version: py-pdf pypdf 6.19.0. Check the vendor advisory for mitigations.

References

• https://github.com/py-pdf/pypdf/commit/959467a9b95be83e2dc5ae873ece5f371263ede7
• https://github.com/py-pdf/pypdf/pull/4087
• https://github.com/py-pdf/pypdf/releases/tag/6.19.0
• https://github.com/py-pdf/pypdf/security/advisories/GHSA-php9-fj8v-98fj

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