Version 2.4.5 of the fastcgi library was released last week: https://github.com/FastCGI-Archives/fcgi2/releases/tag/2.4.5
It fixed CVE-2025-23016, which is described as "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."
The upstream bug report can be found at: https://github.com/FastCGI-Archives/fcgi2/issues/67
and a detailed writeup from the discoverers at: https://www.synacktiv.com/en/publications/cve-2025-23016-exploiting-the-fastcgi-library
which suggests both upgrading to the fixed version and "limiting potential remote access to the FastCGI socket by declaring it as a UNIX socket."
-- -Alan Coopersmith- alan.coopersmith () oracle com Oracle Solaris Engineering - https://blogs.oracle.com/solaris
It was found that the perl Fast CGI module did not properly clean up certain environment variables, related to a particular HTTP request, between subsequent incoming requests. Any environment variable set in the first pass through the code by processing the first request, that wasn't set in some subsequent request, has been added to the hash containing environment variables for that subsequent request. A remote attacker could use this flaw to bypass the authentication process and obtain access to resources, which would be otherwise protected by authentication.
References: [1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=607479
FastCGI (aka fcgi and libfcgi) 2.4.0 allows remote attackers to cause a denial of service (segmentation fault and crash) via a large number of connections.
It was found that the perl Fast CGI module did not properly clean up certain environment variables, related to a particular HTTP request, between subsequent incoming requests. Any environment variable set in the first pass through the code by processing the first request, that wasn't set in some subsequent request, has been added to the hash containing environment variables for that subsequent request. A remote attacker could use this flaw to bypass the authentication process and obtain access to resources, which would be otherwise protected by authentication.
References: [1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=607479