CVE-2026-82398

pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, an attacker can craft a PDF that causes long runtimes when the pypdf/_utils.py function read_until_whitespace reads a stream containing a long run of bytes without whitespace. The function repeatedly performs immutable bytes concatenation in a one-byte loop, causing quadratic processing cost for the long non-whitespace input. This issue is fixed in version 6.15.0.

CVSS 4.0

6.9CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

CVSS 3.1

5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS

0.5% chance of exploitation in the next 30 days; higher than 44% of CVEs (scores of 2026-10-25)

CWE

CWE-407

Published

2026-08-31

Modified

2026-10-05

Record from

the NVD, synced 2026-10-19

Affected

• pypdf_project:pypdf

Packages (OSV)

References

• https://github.com/py-pdf/pypdf/commit/4959848e057e37c218dccad7465259210923faaa
• https://github.com/py-pdf/pypdf/pull/3947
• https://github.com/py-pdf/pypdf/releases/tag/6.15.0
• https://github.com/py-pdf/pypdf/security/advisories/GHSA-fc8x-2rww-xw9m

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