CVE-2025-40931

The module generates a session identifier as an MD5 hash computed from three predictable values: the result of the rand() function (unsuitable for cryptographic applications), epoch time, and the process identifier (PID). The PID comes from a limited range of numbers, the epoch time can be read from the HTTP Date header or guessed, and the built-in rand() function does not provide the required cryptographic randomness. The combination of these weaknesses (CWE-338: use of a cryptographically weak random number generator, CWE-340: generation of predictable numbers) makes the space of possible session identifiers sufficiently small to conduct a brute-force or analytical attack.

A remote unauthenticated attacker can predict the correct session identifier of another user and hijack their session, gaining unauthorized access to protected application resources. This results in a breach of data confidentiality and integrity.

Apply patches available from the vendor according to the references or switch to the Apache::Session::Generate::Random module indicated by the vendor as a secure alternative. Users of Debian-based distributions should verify that the installed libapache-session-perl package includes the patch with Crypt::URandom. It is also recommended to verify the application configuration for the session generator being used.

Apache::Session::Generate::MD5 in all versions up to and including 1.94 for Perl. Debian-based distributions (libapache-session-perl package) may have a patch using Crypt::URandom — the local version should be verified.