CVE-2026-102997 · GHSA-jw7q-gvrg-4vj3
pypdf: Possible long runtimes for partially malformed FlateDecode streams (Follow-up)
- Risk score
- 60/100
- CVSS
- 7.5 v3.1
- Exploit chance (30 days)
- 0.3%
- Published
- 30 Sep 2026
Open in the live forecast Today's forecast
What to know
- What it is
- 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, …
- Affected
- pypdf (pip) < 6.18.1
- Fix
- Upgrade pypdf to 6.18.1 or later.
- Exploitation
- No known exploitation
Why it is Amber
- CVSS 7.5 high
- Remotely exploitable without logging in
- On your watchlist: PyPI
Affected packages
| Package | Ecosystem | Vulnerable | Fixed in |
|---|---|---|---|
| pypdf | pip | < 6.18.1 | 6.18.1 |
References
- https://github.com/advisories/GHSA-jw7q-gvrg-4vj3
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-jw7q-gvrg-4vj3
- https://nvd.nist.gov/vuln/detail/CVE-2026-102997
- https://github.com/py-pdf/pypdf/pull/4073
- https://github.com/py-pdf/pypdf/commit/d9d38cf99b115deb562d3b68f36c33027bc04f79
- https://github.com/py-pdf/pypdf/releases/tag/6.18.1
- https://github.com/advisories/GHSA-jw7q-gvrg-4vj3
Original description
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.
Last activity 30 Sep 2026. Patch Forecast updates every hour.