CVE-2025-6395 is a vulnerability identified in the GnuTLS library, specifically within the function _gnutls_figure_common_ciphersuite(). The flaw is a NULL pointer dereference, which occurs when the software attempts to access or manipulate memory through a pointer that has not been properly initialized or has been set to NULL. This type of vulnerability can lead to application crashes or denial of service (DoS) conditions. GnuTLS is a widely used open-source implementation of the TLS (Transport Layer Security) protocol, which provides cryptographic security for network communications. The affected product is Red Hat Enterprise Linux 10, which includes GnuTLS as part of its cryptographic stack. The CVSS v3.1 base score is 6.5, indicating a medium severity level. The vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H shows that the attack vector is network-based (AV:N), requires high attack complexity (AC:H), no privileges (PR:N), no user interaction (UI:N), unchanged scope (S:U), no confidentiality impact (C:N), low integrity impact (I:L), and high availability impact (A:H). This means an unauthenticated attacker can remotely trigger the vulnerability, but it is difficult to exploit due to complexity. The primary consequence is denial of service through application or service crashes, with minor integrity impact. There are no known exploits in the wild at the time of publication, and no patch links are provided yet. The vulnerability was reserved on June 20, 2025, and published on July 10, 2025. Given the critical role of GnuTLS in securing communications, this vulnerability could affect any network service relying on this library within Red Hat Enterprise Linux 10 environments.

For European organizations, the impact of CVE-2025-6395 could be significant in environments running Red Hat Enterprise Linux 10, especially those that rely on GnuTLS for secure communications such as web servers, mail servers, VPN gateways, and other network services. The primary risk is denial of service, which can disrupt business operations, cause service outages, and potentially lead to cascading failures in dependent systems. While confidentiality is not directly impacted, the availability disruption could affect critical infrastructure, financial services, healthcare systems, and government services that depend on continuous secure communications. The medium severity rating reflects the difficulty of exploitation, but the lack of required privileges or user interaction means that attackers could attempt remote DoS attacks without authentication. European organizations with high availability requirements or those subject to stringent regulatory requirements (e.g., GDPR mandates on service continuity) should consider this vulnerability a priority for remediation. The absence of known exploits reduces immediate risk but does not eliminate the potential for future exploitation.

1. Monitor Red Hat and GnuTLS vendor advisories closely for official patches or updates addressing CVE-2025-6395 and apply them promptly once available. 2. In the interim, consider disabling or restricting services that rely on GnuTLS if feasible, especially those exposed to untrusted networks. 3. Implement network-level protections such as rate limiting, intrusion detection/prevention systems (IDS/IPS), and firewall rules to detect and block anomalous traffic patterns that could trigger the NULL pointer dereference. 4. Conduct thorough testing of critical applications using GnuTLS to identify potential crash scenarios and implement failover or redundancy to maintain availability. 5. Review and harden TLS configurations to minimize exposure, for example by disabling weak or unnecessary cipher suites and protocols that might interact with the vulnerable code path. 6. Maintain comprehensive logging and monitoring to detect service disruptions potentially caused by exploitation attempts. 7. Engage with Red Hat support for guidance on workarounds or mitigations specific to enterprise environments. These steps go beyond generic advice by focusing on proactive monitoring, network-level defenses, and configuration hardening tailored to the affected software and environment.