Junglewise Threat Intelligence

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

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

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

Executive brief

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.

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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