high7.1
CVE-2026-119205
pypdf has possible infinite loop when cloning dictionaries
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | pypdf | < 6.21.4 | 6.21.4 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Py-Pdf | Pypdf | before 6.21.4 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-mfr5-77xh-9j7h
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-mfr5-77xh-9j7h
- https://nvd.nist.gov/vuln/detail/CVE-2026-119205
- https://github.com/py-pdf/pypdf/pull/4288
- https://github.com/py-pdf/pypdf/commit/f176db1a1f7f9af3e472e69a843ef1175653b044
- https://github.com/py-pdf/pypdf/releases/tag/6.21.4