CVE-2025-6395 is a vulnerability identified in the GnuTLS cryptographic library, specifically within the _gnutls_figure_common_ciphersuite() function. 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 results in an application crash, leading to a denial of service (DoS) condition. The vulnerability affects Red Hat Enterprise Linux 10, which includes GnuTLS as part of its cryptographic and TLS/SSL communication stack. The CVSS 3.1 base score is 6.5, indicating medium severity. The vector string (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H) shows that the attack 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 attacker can remotely cause a denial of service by crashing applications or services that rely on the vulnerable GnuTLS function, but cannot gain unauthorized access or modify data. No known exploits are currently reported in the wild, and no patches have been linked yet, though Red Hat is the vendor responsible for issuing fixes. The vulnerability is significant for environments where GnuTLS is used for secure communications, as service interruptions could disrupt operations.

For European organizations, the primary impact of CVE-2025-6395 is the potential for denial of service attacks against systems running Red Hat Enterprise Linux 10 with the vulnerable GnuTLS library. This could disrupt critical services that rely on TLS/SSL communications, such as web servers, VPN gateways, mail servers, and other networked applications. While confidentiality and data integrity are not directly compromised, availability interruptions can lead to operational downtime, loss of productivity, and potential reputational damage. Sectors such as finance, healthcare, government, and telecommunications, which often use Red Hat Enterprise Linux in their infrastructure, could be particularly affected. The high attack complexity reduces the likelihood of widespread exploitation, but targeted attacks against critical infrastructure remain a concern. The absence of known exploits in the wild currently limits immediate risk but vigilance is necessary as attackers may develop exploits once patches are released.

Organizations should monitor Red Hat security advisories closely and apply patches or updates for Red Hat Enterprise Linux 10 as soon as they become available to address this vulnerability. In the interim, administrators can mitigate risk by limiting network exposure of services using GnuTLS, implementing network-level protections such as firewalls and intrusion prevention systems to detect and block anomalous traffic patterns that may trigger the vulnerability. Conducting thorough testing of critical applications that use GnuTLS to identify potential crash scenarios can help prepare for incident response. Employing redundancy and failover mechanisms can reduce service disruption impact. Additionally, organizations should maintain up-to-date backups and incident response plans to quickly recover from potential denial of service events. Regular vulnerability scanning and penetration testing can help identify if vulnerable versions are present in the environment.