Client Nonce Insecurities in Authen::SASL::Perl::DIGEST_MD5 by Authen

CVE-2025-40918

What is CVE-2025-40918?

The Authen::SASL::Perl::DIGEST_MD5 module for Perl exhibits a vulnerability related to the insecure generation of the client nonce (cnonce). This nonce is derived from a combination of the process ID (PID), the current epoch time, and the insecure built-in rand function. The PID is limited to a small range, which may be exploited, coupled with the potential for the epoch time to be guessed if it is not disclosed via the HTTP Date header. According to RFC 2831, a secure implementation of the cnonce should contain at least 64 bits of entropy to defend against chosen plaintext attacks and ensure mutual authentication, highlighting the importance of strengthening the nonce generation process. Users of affected versions are urged to apply a security patch to mitigate this vulnerability.

References