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.
Workaround:
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
| Link | Tags |
|---|---|
| http://www.openwall.com/lists/oss-security/2025/04/23/4 | third party advisory mailing list |
| https://github.com/FastCGI-Archives/fcgi2/issues/67 | exploit issue tracking |
| https://github.com/FastCGI-Archives/fcgi2/releases/tag/2.4.5 | patch release notes |
| https://www.synacktiv.com/en/publications/cve-2025-23016-exploiting-the-fastcgi-library | technical description exploit third party advisory |
| https://github.com/perl-catalyst/FCGI/issues/14 | exploit issue tracking |
| https://patch-diff.githubusercontent.com/raw/FastCGI-Archives/fcgi2/pull/74.patch | patch |