pypdf is a free and open-source pure-python PDF library. Prior to 6.21.3, pypdf can consume excessive memory while opening a crafted PDF containing cross-reference streams that declare very large entry counts. Highly compressible streams and /Prev chains can multiply the number of parsed entries across a document, while negative /Index counts can bypass the existing per-stream clamp. This issue is fixed in version 6.21.3.
Fix
Nothing published yet: no patch, vendor advisory or mitigation reference on NVD, no vendor advisory in the News for this CVE, not in CISA's KEV, no fixed package version. BaselineWatch does not guess at one.
Change history 1
- First seenCVSS 7.1 · py-pdfNVD modified 2026-10-29 20:43
Affected (CPE criteria) 0
NVD has not attached CPE configurations yet.
References 4
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-x3rh-gjgm-fmqc x_refsource_confirm
- https://github.com/py-pdf/pypdf/pull/4269 x_refsource_misc
- https://github.com/py-pdf/pypdf/commit/a93fe3a901fd00af38f0a105c3ba7175fa72dcb4 x_refsource_misc
- https://github.com/py-pdf/pypdf/releases/tag/6.21.3 x_refsource_misc