pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop when cloning or duplicating a crafted cyclic DictionaryObject. Clone traversal checked generated destination references rather than the original source references, allowing some source cycles to evade the visited-object check. This issue is fixed in version 6.21.4.
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 20:35
Affected (CPE criteria) 0
NVD has not attached CPE configurations yet.
References 4
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-mfr5-77xh-9j7h x_refsource_confirm
- https://github.com/py-pdf/pypdf/pull/4288 x_refsource_misc
- https://github.com/py-pdf/pypdf/commit/f176db1a1f7f9af3e472e69a843ef1175653b044 x_refsource_misc
- https://github.com/py-pdf/pypdf/releases/tag/6.21.4 x_refsource_misc