pypdf is a free and open-source pure-python PDF library.
CVE-2026-102997
pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF containing a partially malformed /FlateDecode stream with padded data can force pypdf/filters.py to use inefficient byte-by-byte decompression while the earlier recovery counter fails to advance for bytes that successfully decode, causing long runtimes and application unavailability. This is a residual issue after the malformed FlateDecode recovery fix. This issue is fixed in version 6.18.1.
Assessment
- CVSS
- 8.7 (v4.0)
- Severity
- High
- EPSS
- 0.34% chance of exploitation in the next 30 days
- Known exploited
- Not listed in CISA KEV
- Exploit availability
- Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
- Published
- 30 September 2026
- Last updated
- 2 November 2026
- Weakness
- CWE-400, CWE-407
- Assigner
- security-advisories@github.com
CVSS vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
At the source
References
- https://github.com/py-pdf/pypdf/commit/d9d38cf99b115deb562d3b68f36c33027bc04f79
- https://github.com/py-pdf/pypdf/pull/4073
- https://github.com/py-pdf/pypdf/releases/tag/6.18.1
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-jw7q-gvrg-4vj3
- https://nvd.nist.gov/vuln/detail/CVE-2026-102997
- https://github.com/advisories/GHSA-jw7q-gvrg-4vj3
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