CVE-2025-40920 is a high-severity vulnerability affecting the Perl module Catalyst::Authentication::Credential::HTTP, specifically versions 1.018 and earlier, including version 0.06. The vulnerability arises from the use of the Perl Data::UUID library to generate nonces for HTTP authentication. Data::UUID generates version 3 UUIDs, which are name-based and derived from known inputs, making them predictable and unsuitable for security-sensitive operations such as nonce generation. According to RFC 9562 and RFC 7616, nonces used in HTTP authentication must be generated from strong cryptographic sources to ensure unpredictability and prevent replay or impersonation attacks. The predictable nature of the nonces generated by Data::UUID compromises the confidentiality and integrity of the authentication process, potentially allowing attackers to guess or reproduce valid nonces, bypass authentication mechanisms, or conduct replay attacks. The vulnerability has a CVSS v3.1 base score of 8.6, reflecting its network attack vector, low attack complexity, no privileges or user interaction required, and significant impact on confidentiality with partial impact on integrity and availability. There are no known exploits in the wild yet, and no patches have been linked at the time of publication. The root cause is the use of a non-cryptographically secure UUID generation method for security-critical nonce values, violating best practices for cryptographic nonce generation.

For European organizations using Catalyst::Authentication::Credential::HTTP in their Perl-based web applications or services, this vulnerability poses a significant risk. Attackers could exploit predictable nonces to bypass HTTP authentication, leading to unauthorized access to sensitive systems and data. This can result in data breaches, exposure of confidential information, and potential disruption of services. Given the high CVSS score and the network-exploitable nature of the vulnerability, attackers can remotely target vulnerable systems without authentication or user interaction. The partial impact on integrity and availability means attackers could also manipulate authentication flows or cause denial of service. Organizations in sectors with high reliance on Perl web frameworks, such as government, finance, and critical infrastructure, are particularly at risk. The lack of known exploits currently provides a window for proactive mitigation before active exploitation occurs.

European organizations should immediately audit their use of Catalyst::Authentication::Credential::HTTP and identify affected versions, particularly version 0.06 and earlier. Since no official patches are currently linked, organizations should consider the following specific mitigations: 1) Replace the nonce generation mechanism with a cryptographically secure random number generator compliant with RFC 7616, such as using Perl modules like Crypt::URandom or Crypt::Random to generate nonces. 2) If feasible, upgrade to a newer version of Catalyst::Authentication::Credential::HTTP that addresses this vulnerability once available. 3) Implement additional layers of authentication or multi-factor authentication to reduce reliance on nonce security alone. 4) Monitor authentication logs for unusual patterns indicative of replay or brute force attacks exploiting predictable nonces. 5) Engage with the Perl and Catalyst community to track patch releases and security advisories. 6) Conduct penetration testing focusing on HTTP authentication mechanisms to validate the effectiveness of mitigations.