CVE-2025-32989: 
GnuTLS vulnerability analysis and mitigation

A heap-buffer-overread vulnerability (CVE-2025-32989) was discovered in GnuTLS affecting how it handles the Certificate Transparency (CT) Signed Certificate Timestamp (SCT) extension during X.509 certificate parsing. The vulnerability was reported by the OpenAI Security Research Team and fixed in GnuTLS version 3.8.10. The issue affects multiple Linux distributions including Red Hat Enterprise Linux, Ubuntu, and Debian (Debian Security, Ubuntu Security, Red Hat CVE).

The vulnerability occurs when processing X.509 certificates containing malformed SCT extensions (OID 1.3.6.1.4.1.11129.2.4.2). The flaw allows reading beyond the memory buffer boundary when the length field of the SCT extension is malformed. The vulnerability has been assigned a CVSS v3.1 base score of 5.3 (Medium) with the following vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N. The issue can be effectively mitigated by compiling the library with -DFORTIFYSOURCE=2 (OSS Security, Snyk).

When exploited, this vulnerability can lead to the exposure of confidential information when GnuTLS verifies certificates from certain websites where the SCT is not checked correctly. The information disclosure occurs specifically when the SCT log_id is logged, exported, or otherwise exposed by applications using the GnuTLS client library (Red Hat CVE).

The vulnerability has been fixed in GnuTLS version 3.8.10. Users are recommended to upgrade to this version or later. For Ubuntu systems, updates are available for versions 25.04 (3.8.9-2ubuntu3.1), 24.04 (3.8.3-1.1ubuntu3.4), and 22.04 (3.7.3-4ubuntu1.7). Debian has also released fixes in version 3.7.9-2+deb12u5 for bookworm and 3.8.9-3 for sid and trixie (Ubuntu Security, Debian Security).