CVE-2026-119206: pypdf: Possible long runtimes when retrieving page labels

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-400

Description

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.3, pypdf can take excessive time to retrieve page labels from a crafted PDF containing a flat page-label number tree with many ranges. The page_labels property resolves each page independently and repeatedly scans the same /Nums array from the beginning, causing work to grow with both the page count and the number of label ranges. This issue is fixed in version 6.21.3.

Affected products

py-pdf pypdf: before 6.21.3

References

https://github.com/py-pdf/pypdf/commit/b891fef37000cd86baa6e9848a3387d080b3b03e
https://github.com/py-pdf/pypdf/pull/4251
https://github.com/py-pdf/pypdf/releases/tag/6.21.3
https://github.com/py-pdf/pypdf/security/advisories/GHSA-42gh-23hr-vphw

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