CVE-2025-32989 is a vulnerability identified in the GnuTLS library, specifically in how it processes the Certificate Transparency (CT) Signed Certificate Timestamp (SCT) extension during X.509 certificate parsing. The SCT extension, identified by OID 1.3.6.1.4.1.11129.2.4.2, is designed to provide transparency and accountability for issued certificates by including signed timestamps. However, due to improper validation, a heap-buffer-overread occurs when GnuTLS encounters a malformed SCT extension. This memory overread can lead to the exposure of sensitive data residing in memory buffers during the certificate verification process. The vulnerability affects Red Hat Enterprise Linux 10, which uses GnuTLS for TLS communications. The flaw can be triggered remotely without requiring authentication or user interaction, as it occurs during the TLS handshake when verifying certificates from certain websites. The CVSS 3.1 base score is 5.3 (medium), reflecting the network attack vector, low complexity, no privileges required, no user interaction, and limited confidentiality impact without affecting integrity or availability. No known exploits have been reported in the wild, but the vulnerability poses a risk of confidential information leakage, potentially including cryptographic material or other sensitive data in memory. The issue highlights the importance of robust parsing and validation of certificate extensions in cryptographic libraries.

For European organizations, this vulnerability could lead to the unintended disclosure of sensitive information during TLS communications, particularly when connecting to or verifying certificates from malicious or compromised servers presenting crafted SCT extensions. This exposure could compromise confidentiality of cryptographic operations or other sensitive data held in memory buffers during certificate validation. Organizations relying on Red Hat Enterprise Linux 10 and GnuTLS for secure communications, including government agencies, financial institutions, healthcare providers, and critical infrastructure operators, may face increased risk of data leakage. Although the vulnerability does not directly allow code execution or service disruption, the confidentiality breach could facilitate further attacks or espionage. The medium severity indicates a moderate risk that should be addressed promptly to maintain trust in TLS communications and protect sensitive data. The lack of known exploits reduces immediate urgency but does not eliminate the threat, especially given the remote and unauthenticated nature of the vulnerability.

1. Apply official patches and updates from Red Hat as soon as they become available to address the vulnerability in GnuTLS. 2. Until patches are deployed, consider implementing network-level controls such as TLS interception and inspection to detect and block suspicious certificates with malformed SCT extensions. 3. Enforce strict certificate validation policies and monitor TLS traffic for anomalies related to certificate extensions. 4. Use alternative cryptographic libraries or TLS implementations that are not affected by this vulnerability if immediate patching is not feasible. 5. Conduct regular security audits and penetration testing focusing on TLS implementations and certificate handling. 6. Educate security teams about the risks of malformed certificate extensions and ensure incident response plans include scenarios involving TLS certificate manipulation. 7. Monitor threat intelligence feeds for any emerging exploits targeting this vulnerability to enable rapid response.