An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires reading a file in non-strict mode.
This has been fixed in pypdf==6.9.2.
If users cannot upgrade yet, consider applying the changes from PR #3693.
6.9.2Exploitability
AV:NAC:LAT:PPR:NUI:NVulnerable System
VC:NVI:NVA:HSubsequent System
SC:NSI:NSA:N4.6/CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U