CVE-2025-40920 identifies a cryptographic weakness in the Catalyst::Authentication::Credential::HTTP Perl module, specifically in versions 1.018 and earlier. The module generates nonces for HTTP authentication using the Data::UUID library, which produces version 3 UUIDs. Version 3 UUIDs are generated deterministically from namespace and name inputs, making them predictable and unsuitable for security-sensitive nonce generation. RFC 7616 mandates that nonces used in HTTP Digest Authentication must be generated from strong cryptographic random sources to prevent replay and impersonation attacks. The use of Data::UUID violates this requirement, exposing systems to potential replay attacks where an attacker can reuse or predict nonces to bypass authentication checks. The vulnerability has a CVSS 3.1 base score of 8.6 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L), indicating it can be exploited remotely without privileges or user interaction, causing high confidentiality impact, limited integrity impact, and low availability impact. Although no exploits are currently known in the wild, the predictable nonce generation represents a significant cryptographic flaw that undermines the security of HTTP authentication mechanisms relying on this module. The vulnerability is tracked under CWE-340 (Generation of Predictable Numbers or Identifiers). No official patches are currently linked, so remediation involves replacing the nonce generation method with a cryptographically secure random number generator compliant with RFC 7616 standards.

For European organizations, this vulnerability poses a serious risk to web applications and services that utilize Catalyst::Authentication::Credential::HTTP for HTTP authentication. Attackers can exploit predictable nonces to perform replay attacks, potentially gaining unauthorized access to sensitive systems or data. This can lead to confidentiality breaches, unauthorized data exposure, and partial integrity compromise. Critical sectors such as finance, healthcare, government, and telecommunications that rely on Perl-based legacy or custom authentication systems are particularly vulnerable. The ease of remote exploitation without authentication or user interaction increases the threat level. Additionally, organizations failing to update or patch this vulnerability may face compliance issues with GDPR and other data protection regulations due to the risk of unauthorized data access. The lack of known exploits in the wild currently reduces immediate risk but does not diminish the urgency of mitigation given the high CVSS score and the fundamental cryptographic weakness.

European organizations should immediately audit their use of Catalyst::Authentication::Credential::HTTP to identify affected versions (1.018 and earlier). Since no official patches are currently available, developers should modify the nonce generation logic to use a cryptographically secure random number generator, such as Perl's Crypt::Random or Crypt::URandom modules, ensuring compliance with RFC 7616. Implementing nonces with sufficient entropy and unpredictability is critical. Additionally, organizations should monitor vendor announcements for official patches or updates. Employing web application firewalls (WAFs) to detect and block replay attack patterns can provide interim protection. Regular code reviews and penetration testing focused on authentication mechanisms should be conducted. Finally, organizations should ensure logging and alerting are in place to detect suspicious authentication attempts that may indicate exploitation attempts.