CVE-2025-2814 identifies a vulnerability in the Crypt::CBC Perl module versions 1.21 through 3.05, specifically related to the use of a cryptographically weak pseudo-random number generator (PRNG). Crypt::CBC is a widely used Perl module that provides Cipher Block Chaining (CBC) mode encryption functionality. The vulnerability arises when the module attempts to generate entropy for cryptographic operations on systems where the standard secure entropy source, /dev/urandom, is unavailable. In such cases, Crypt::CBC falls back to using the Perl rand() function as the entropy source. The rand() function is not designed for cryptographic purposes and produces predictable outputs, which significantly weakens the cryptographic strength of any keys or initialization vectors generated using it. This weakness can lead to reduced confidentiality guarantees, as attackers with knowledge or ability to predict the rand() output could potentially recover encryption keys or plaintext data. The vulnerability is classified under CWE-338, which covers the use of cryptographically weak PRNGs. The CVSS v3.1 base score is 4.0 (medium severity), reflecting that exploitation requires local access (AV:L), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction (UI:N). The impact is limited to availability (A:L), indicating that the primary consequence is a potential denial of service or degraded cryptographic function rather than direct confidentiality or integrity compromise. No known exploits are currently reported in the wild, and no patches are explicitly linked, suggesting that mitigation may require manual updates or configuration changes. This vulnerability is particularly relevant for environments running Perl applications that rely on Crypt::CBC for encryption on operating systems lacking /dev/urandom, such as some embedded systems or legacy platforms. The fallback to rand() undermines cryptographic robustness and could facilitate cryptanalysis or key recovery attacks if exploited.

For European organizations, the impact of CVE-2025-2814 depends largely on their use of Perl applications that incorporate Crypt::CBC for encryption, especially in environments where /dev/urandom is not available. Organizations operating legacy or embedded systems without secure entropy sources are at higher risk. The use of a weak PRNG compromises the strength of cryptographic keys and initialization vectors, potentially enabling attackers to decrypt sensitive data or impersonate legitimate users if keys are predictable. Although the CVSS score indicates a medium severity with limited impact on confidentiality and integrity, the practical risk could be higher in scenarios where encryption is critical for protecting sensitive personal data, intellectual property, or secure communications. This is particularly relevant under the GDPR framework, where any compromise of personal data confidentiality can lead to significant regulatory and reputational consequences. Additionally, the vulnerability could affect availability if cryptographic operations fail or behave unpredictably due to weak entropy. European sectors such as finance, healthcare, government, and critical infrastructure that rely on Perl-based cryptographic modules in constrained environments may face increased exposure. The absence of known exploits suggests a window for proactive mitigation before active exploitation occurs.

1. Verify the operating environment to ensure that /dev/urandom or an equivalent cryptographically secure entropy source is available and accessible to Perl applications using Crypt::CBC. 2. Upgrade Crypt::CBC to the latest version beyond 3.05 where this fallback behavior is corrected or mitigated. If no official patch is available, consider applying custom patches or configuration changes to force the use of secure entropy sources. 3. For embedded or legacy systems lacking /dev/urandom, implement alternative secure entropy sources such as hardware random number generators or software-based cryptographically secure PRNGs and configure Crypt::CBC to utilize them. 4. Audit all Perl applications using Crypt::CBC to identify those potentially affected and prioritize remediation based on sensitivity of encrypted data and system criticality. 5. Implement monitoring for unusual cryptographic failures or anomalies that could indicate exploitation attempts. 6. Educate development and operations teams about the risks of using non-cryptographic PRNGs in security-sensitive contexts and enforce secure coding practices. 7. Where feasible, replace Crypt::CBC with more modern cryptographic libraries that have robust entropy management and are actively maintained. 8. Conduct penetration testing and cryptanalysis assessments on affected systems to evaluate the practical impact of weak PRNG usage and validate mitigation effectiveness.