medium6.9
CVE-2026-27026
pypdf possibly has long runtimes for malformed FlateDecode streams
Impact
### Impact An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires a malformed `/FlateDecode` stream, where the byte-by-byte decompression is used. ### Patches This has been fixed in [pypdf==6.7.1](https://github.com/py-pdf/pypdf/releases/tag/6.7.1). ### Workarounds If you cannot upgrade yet, consider applying the changes from PR [#3644](https://github.com/py-pdf/pypdf/pull/3644).
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | pypdf | < 6.7.1 | 6.7.1 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Pypdf Project | Pypdf | before 6.7.1 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016
- https://github.com/py-pdf/pypdf/pull/3644
- https://github.com/py-pdf/pypdf/releases/tag/6.7.1
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8h
- https://github.com/advisories/GHSA-9mvc-8737-8j8h
- https://nvd.nist.gov/vuln/detail/CVE-2026-27026