Moderate severityNVD Advisory· Published Feb 20, 2026· Updated Feb 24, 2026
pypdf possibly has long runtimes for malformed FlateDecode streams
CVE-2026-27026
Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.7.1, 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. This vulnerability is fixed in 6.7.1.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
pypdfPyPI | < 6.7.1 | 6.7.1 |
Affected products
6- osv-coords5 versionspkg:apk/chainguard/open-webuipkg:apk/wolfi/open-webuipkg:pypi/pypdfpkg:rpm/opensuse/python-PyPDF2&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/python-PyPDF2&distro=openSUSE%20Tumbleweed
< 0.8.3-r1+ 4 more
- (no CPE)range: < 0.8.3-r1
- (no CPE)range: < 0.8.3-r1
- (no CPE)range: < 6.7.1
- (no CPE)range: < 2.11.1-bp160.2.1
- (no CPE)range: < 2.11.1-4.1
Patches
Vulnerability mechanics
References
6- github.com/advisories/GHSA-9mvc-8737-8j8hghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-27026ghsaADVISORY
- github.com/py-pdf/pypdf/commit/7905842d833f899f1d3228af7e7467ad80277016ghsax_refsource_MISCWEB
- github.com/py-pdf/pypdf/pull/3644ghsax_refsource_MISCWEB
- github.com/py-pdf/pypdf/releases/tag/6.7.1ghsax_refsource_MISCWEB
- github.com/py-pdf/pypdf/security/advisories/GHSA-9mvc-8737-8j8hghsax_refsource_CONFIRMWEB
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