CVE-2025-40920 identifies a cryptographic weakness in the nonce generation mechanism of Catalyst::Authentication::Credential::HTTP, a Perl module used for HTTP authentication. Versions 1.018 and earlier rely on the Perl Data::UUID library to generate nonces, which produces version 3 UUIDs. These UUIDs are generated deterministically from namespace and name inputs rather than from a cryptographically secure random source, making them predictable. According to RFC 9562 and RFC 7616, nonces used in HTTP authentication must be generated from strong cryptographic random sources to prevent replay and impersonation attacks. The use of predictable nonces undermines the confidentiality and integrity of the authentication process, as attackers can precompute or guess nonce values to bypass authentication or launch replay attacks. The vulnerability has a CVSS 3.1 base score of 8.6, reflecting its network attack vector, low attack complexity, no privileges or user interaction required, and high impact on confidentiality with partial impacts on integrity and availability. Although no exploits have been reported in the wild, the weakness presents a significant risk to systems relying on this module for authentication. The vulnerability affects version 0.06 and earlier of the Catalyst::Authentication::Credential::HTTP module, and no official patches have been linked yet. The root cause is the inappropriate use of Data::UUID for nonce generation, which should be replaced by a cryptographically secure random number generator compliant with RFC 7616 recommendations.

For European organizations, this vulnerability poses a significant risk to web applications and services that utilize the Catalyst::Authentication::Credential::HTTP module for HTTP authentication. Exploitation could lead to unauthorized access by allowing attackers to predict or replay authentication nonces, compromising sensitive data confidentiality and potentially disrupting service availability. Sectors such as finance, healthcare, government, and critical infrastructure that rely on Perl-based web frameworks for secure authentication are particularly vulnerable. The predictability of nonces may facilitate man-in-the-middle or replay attacks, undermining trust in authentication mechanisms and potentially leading to data breaches or service interruptions. Given the high CVSS score and network exploitable nature, attackers can remotely exploit this vulnerability without authentication or user interaction, increasing the threat surface. The absence of known exploits in the wild suggests a window for proactive mitigation before widespread exploitation occurs.

European organizations should immediately audit their use of Catalyst::Authentication::Credential::HTTP modules to identify affected versions (1.018 and earlier, specifically 0.06). Since no official patches are currently linked, developers should modify the nonce generation code to replace Data::UUID-based version 3 UUIDs with nonces generated from a cryptographically secure random number generator, such as Perl's Crypt::Random or other libraries compliant with RFC 7616. Implementing nonce generation using secure random sources will prevent predictability and strengthen authentication security. Additionally, organizations should monitor their web authentication logs for unusual or repeated nonce values that could indicate attempted exploitation. Applying strict access controls and network segmentation around affected services can reduce exposure. Finally, maintain vigilance for vendor updates or patches and apply them promptly once available. Incorporating security code reviews focusing on cryptographic practices in authentication modules is recommended to prevent similar issues.