FCGI versions 0.44 through 0.82, for Perl, include a vulnerable version of the FastCGI fcgi2 (aka fcgi) library. The included FastCGI library is affected by CVE-2025-23016, causing an integer overflow (and resultant heap-based buffer overflow) via crafted nameLen or valueLen values in data to the IPC socket. This occurs in ReadParams in fcgiapp.c.
o Restore old behavior when un-downgradeable uft8 is sent to FCGI. The first time this happens, a warning will be issued, but subsequently the bytes will be sent through raw (causing double encoding etc). If the character string can be downgraded safely, then it will still be. use warnings FATAL => 'utf8'; can be used to make undowngradeable strings throw an exception. o Fix PRINT retval (Closes: RT#57697).