CVE-2026-119203: pypdf: Possible infinite loop when hitting EOF in standard xref table during trailer search

Severity: high (CVSS 7.1 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-29 · updated 2026-10-30
Weakness: CWE-835

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.4, pypdf can enter an infinite loop while opening a crafted incomplete PDF whose standard cross-reference table reaches the end of the file without a trailer. The trailer search can repeatedly rewind to the same stream position instead of terminating when parsing makes no progress, blocking the processing thread. This issue is fixed in version 6.21.4.

Affected products

py-pdf pypdf: before 6.21.4

References

https://github.com/py-pdf/pypdf/commit/06593f993789a4b573dd955730c1a7051128bb2a
https://github.com/py-pdf/pypdf/pull/4289
https://github.com/py-pdf/pypdf/releases/tag/6.21.4
https://github.com/py-pdf/pypdf/security/advisories/GHSA-5849-834g-hvw5

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