CVE-2025-32989 is a medium-severity vulnerability affecting Red Hat Enterprise Linux 10, specifically in the GnuTLS library's handling of the Certificate Transparency (CT) Signed Certificate Timestamp (SCT) extension during X.509 certificate parsing. The vulnerability arises from a heap-buffer-overread condition triggered when GnuTLS processes a malformed SCT extension identified by the OID 1.3.6.1.4.1.11129.2.4.2. This malformed SCT can be crafted by an attacker to cause GnuTLS to read beyond the allocated buffer, leading to exposure of sensitive information present in adjacent memory regions. The flaw does not require any privileges or user interaction to be exploited and can be triggered remotely by presenting a specially crafted certificate during TLS handshake verification. The impact is limited to confidentiality as the attacker can potentially obtain sensitive data from the memory of the affected system during certificate validation. There is no indication that integrity or availability are impacted. The vulnerability is present in Red Hat Enterprise Linux 10 due to its use of the vulnerable GnuTLS version. No known exploits are currently reported in the wild, and no patches or mitigations have been explicitly linked yet. The CVSS v3.1 base score is 5.3, reflecting a network attack vector, low attack complexity, no privileges required, no user interaction, unchanged scope, and limited confidentiality impact.

For European organizations, this vulnerability poses a risk primarily to systems running Red Hat Enterprise Linux 10 that rely on GnuTLS for TLS certificate validation, such as web servers, mail servers, or client applications performing certificate verification. The exposure of sensitive data from memory during certificate validation could lead to leakage of confidential information, potentially including cryptographic material or other sensitive runtime data. While the vulnerability does not allow direct code execution or denial of service, the confidentiality breach could facilitate further attacks or data exfiltration. Organizations in sectors handling sensitive or regulated data (financial, healthcare, government) may face compliance and reputational risks if sensitive information is leaked. The risk is heightened in environments where untrusted or malicious TLS certificates might be encountered, such as public-facing services or systems interacting with external partners. However, the lack of known exploits and the medium severity rating suggest the immediate threat level is moderate but warrants timely attention.

To mitigate this vulnerability, European organizations should: 1) Monitor Red Hat and GnuTLS advisories closely for official patches or updates addressing CVE-2025-32989 and apply them promptly once available. 2) Temporarily restrict or scrutinize incoming TLS connections from untrusted or unknown sources to reduce exposure to malicious certificates containing malformed SCT extensions. 3) Consider deploying network-level TLS inspection or proxy solutions that can detect and block anomalous certificates with malformed SCT extensions. 4) Audit and update all systems running Red Hat Enterprise Linux 10 to ensure they are running the latest GnuTLS versions and related security patches. 5) Implement strict certificate validation policies and use certificate pinning or trusted certificate stores to minimize reliance on potentially malicious certificates. 6) Conduct internal security assessments to identify systems that perform certificate validation using GnuTLS and prioritize their patching and monitoring. These steps go beyond generic advice by focusing on certificate-specific controls and proactive monitoring of TLS traffic for malformed SCT extensions.