Infinite Loop Vulnerability in pypdf Library by PyPDF
CVE-2026-119205

7.1HIGH

Key Information:

Vendor

Py-PDF

Status
PyPDF
Vendor
CVE Published:
29 October 2026

What is CVE-2026-119205?

The pypdf library, a free and open-source pure-Python PDF manipulation tool, is susceptible to an infinite loop condition when handling crafted cyclic DictionaryObjects. Specifically, prior to version 6.21.4, the cloning process improperly checked references during clone traversal, leading to potential denial-of-service situations via unvisited source cycles. This issue has been resolved in version 6.21.4, and users are strongly advised to update to this version to maintain the integrity and availability of their PDF processing capabilities.

Affected Version(s)

pypdf < 6.21.4

References

https://github.com/py-pdf/pypdf/security/advisories/GHSA-...
x_refsource_CONFIRM
https://github.com/py-pdf/pypdf/pull/4288
x_refsource_MISC
https://github.com/py-pdf/pypdf/commit/f176db1a1f7f9af3e4...
x_refsource_MISC

CVSS V4

Score:
7.1
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.