CVE-2026-42010

Publication date 7 May 2026

Last updated 20 May 2026

Ubuntu priority

Cvss 3 Severity Score

Description

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.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
gnutls28	26.04 LTS resolute	Fixed 3.8.12-2ubuntu1.1
	25.10 questing	Fixed 3.8.9-3ubuntu2.2
	24.04 LTS noble	Fixed 3.8.3-1.1ubuntu3.6
	22.04 LTS jammy	Fixed 3.7.3-4ubuntu1.9
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
gnutls28	Upstream: cb1833a

Severity score breakdown

Parameter	Value
Base score	7.1 · High
Attack vector	Network
Attack complexity	Low
Privileges required	Low
User interaction	None
Scope	Unchanged
Confidentiality	High
Integrity impact	Low
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

References

Related Ubuntu Security Notices (USN)

USN-8284-1
GnuTLS vulnerabilities
20 May 2026