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7.1High

Gnu Gnutls

CVE-2026-42010

A flaw was found in gnutls. Servers configured with RSA-PSK (Rivest–Shamir–Adleman – Pre-Shared Key) wrongfully matched usernames containing a NUL character with truncated usernames. A remote attacker could exploit this by sending a specially crafted username, leading to an authentication bypass. This vulnerability allows an attacker to gain unauthorized access by circumventing the authentication process.

What this means for your business

  • It affects Gnutls. It matters if your company, or a supplier that handles your data, runs it.
  • An attacker can use it remotely, over a network, with an ordinary user login, and without anyone at your company clicking anything.
  • FIRST's prediction model gives it a 1% chance of attack attempts being seen in the next 30 days, ranking above 62% of all known flaws.

What to do

  1. 1Check whether your company or your suppliers run Gnutls, and which version. The affected versions are listed further down this page.
  2. 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.

Not sure if your company is exposed?

Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.

Check if you’re exposedBook a call

Scoring

CVSS
7.1 (v3.1)
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Weakness
CWE-170
Assigned by
secalert@redhat.com

Dates

Published
2026-05-07
Last modified
2026-09-18
Sources
NVD

Affected products

  • Gnu Gnutlsall versions
  • Redhat Hardened Imagesall versions
  • Redhat Openshift Container Platform4.0
  • Redhat Enterprise Linux6.0, 7.0, 8.0, 9.0, 10.0

As listed in the NVD configuration data. Not a statement about your estate.

References