CVE-2025-6395: GnuTLS NULL pointer dereference in _gnutls_figure_common_ciphersuite

CVE-2025-6395 · Severity: medium · CVSS 6.5 · Published 2025-07-10

GnuTLS is a widely used security library that enables encrypted communications for Linux systems and various applications. A flaw was found that could allow an attacker to crash services using this library by sending specifically crafted network traffic during the initial connection setup. This results in a denial-of-service, potentially taking down web servers, VPNs, or other secure communication channels.

Technologies: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9. Vendors: Red Hat.

Quick answers

Is CVE-2025-6395 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2025-6395 being exploited in the wild.
How severe is CVE-2025-6395?
Medium severity, with a CVSS score of 6.5, published 10 July 2025.
Which products and versions are affected?
Red Hat Enterprise Linux 10 < 3.8.9-9.el10_0.14; Red Hat Enterprise Linux 8 < 3.6.16-8.el8_10.4; Red Hat Enterprise Linux 9 < 3.8.3-6.el9_6.2.
Is there a fix for CVE-2025-6395?
A patch was published on 2025-07-08: GnuTLS 3.8.10 released with fix Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2025-6395 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2025-6395?
Check whether you run Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8 or Red Hat Enterprise Linux 9 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A NULL pointer dereference vulnerability exists in GnuTLS within the _gnutls_figure_common_ciphersuite() function. The flaw is triggered during the negotiation of common ciphersuites between a client and server. An unauthenticated remote attacker can exploit this by sending a specially crafted handshake, causing the application linked against GnuTLS to terminate unexpectedly. While the attack vector is network-based, the complexity is rated as high, likely due to specific preconditions required in the ciphersuite selection logic. The issue is addressed in GnuTLS version 3.8.10 and various vendor-specific patches.

Affected products

  • GnuTLS GnuTLS < 3.8.10
  • Red Hat Red Hat Enterprise Linux 8 < 3.6.16-8.el8_10.4
  • Red Hat Red Hat Enterprise Linux 9 < 3.8.3-6.el9_6.2
  • Red Hat Red Hat Enterprise Linux 10 < 3.8.9-9.el10_0.14

Timeline

  • 2025-07-08: patched: GnuTLS 3.8.10 released with fix
  • 2025-07-10: disclosed: NVD publication date
  • 2025-09-17: advisory: Red Hat security advisories issued

References

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