CVE-2025-32989 is a heap-buffer-overread vulnerability discovered in the GnuTLS library, specifically in the handling of the Certificate Transparency (CT) Signed Certificate Timestamp (SCT) extension during the parsing of X.509 certificates. The SCT extension, identified by OID 1.3.6.1.4.1.11129.2.4.2, is used to provide proof that a certificate has been logged in a public CT log, enhancing transparency and trust in certificate issuance. However, in this vulnerability, GnuTLS does not properly validate the SCT extension's structure, allowing a maliciously crafted certificate to cause a heap-buffer-overread. This memory access flaw can lead to the exposure of sensitive data from the process memory during certificate verification. The vulnerability affects Red Hat Enterprise Linux 10, which bundles GnuTLS for TLS communications. The CVSS v3.1 base score is 5.3, reflecting a medium severity with a vector indicating network attack vector, low attack complexity, no privileges required, no user interaction, unchanged scope, and confidentiality impact only. The flaw does not affect integrity or availability. No patches or exploits are currently reported, but the flaw could be exploited remotely by presenting a malicious certificate during TLS handshake. The issue is significant because it undermines the confidentiality guarantees of TLS connections relying on GnuTLS, potentially leaking sensitive information to attackers. This vulnerability highlights the importance of robust certificate parsing and validation in cryptographic libraries.

For European organizations, this vulnerability poses a confidentiality risk during TLS communications, potentially exposing sensitive data processed by applications using GnuTLS on Red Hat Enterprise Linux 10. Sectors such as finance, healthcare, government, and critical infrastructure that rely heavily on secure communications could be targeted to extract confidential information. Although the vulnerability does not affect integrity or availability, the leakage of sensitive data could lead to further attacks, loss of trust, regulatory non-compliance (e.g., GDPR), and reputational damage. The remote exploitability without authentication or user interaction increases the risk profile, especially for publicly accessible services. Organizations using GnuTLS in client or server roles must consider the risk of man-in-the-middle or malicious certificate injection attacks. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate it, emphasizing the need for proactive mitigation.

1. Monitor Red Hat and GnuTLS vendor advisories closely and apply security patches promptly once released to address CVE-2025-32989. 2. Until patches are available, consider disabling or restricting the acceptance of SCT extensions in TLS configurations if feasible, or use alternative TLS libraries not affected by this vulnerability. 3. Implement strict certificate validation policies, including pinning trusted certificates or certificate authorities to reduce exposure to malicious certificates. 4. Employ network security controls such as TLS interception detection, anomaly detection, and intrusion prevention systems to identify suspicious certificate-related activities. 5. Conduct thorough security testing and code audits for applications relying on GnuTLS to identify potential exposure. 6. Educate security teams about this vulnerability to ensure rapid response and incident handling if exploitation attempts are detected. 7. Review and enhance logging and monitoring around TLS handshake failures or unusual certificate presentations to detect exploitation attempts early.