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.
- Published Aug 31, 2026
- CVSS 6.9 medium
- 0.5% chance of exploitation in the next 30 days (EPSS)
- A fix is available