pypdf: Possible long runtimes for zero-only width values in cross-reference streamsuntimes for zero-only width values in cross-reference streams

Impact

An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with /W [0 0 0] values and large /Size values.

Patches

This has been fixed in pypdf==6.12.0.

Workarounds

If developers are unable to upgrade their apps immediately, they should consider applying the changes from PR #3791.