zlib before 1.3.2 allows CPU consumption via crc32_combine64 and crc32_combine_gen64 because x2nmodp can do right shifts within a loop that has no termination condition.
https://ostif.org/zlib-audit-complete/
https://github.com/madler/zlib/releases/tag/v1.3.2
https://github.com/madler/zlib/issues/904
https://7asecurity.com/reports/pentest-report-zlib-RC1.1.pdf