CVE-2026-42009

Publication date 30 April 2026

Last updated 6 July 2026

Ubuntu priority

Cvss 3 Severity Score

Description

A flaw was found in gnutls. A remote attacker could exploit an issue in the Datagram Transport Layer Security (DTLS) packet reordering logic. The comparator function, responsible for ordering DTLS packets by sequence numbers, did not correctly handle packets with duplicate sequence numbers. This could lead to unstable packet ordering or undefined behavior, resulting in a denial of service.

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	Fixed 3.6.13-2ubuntu1.12+esm2
	18.04 LTS bionic	Fixed 3.5.18-1ubuntu1.6+esm3
	16.04 LTS xenial	Fixed 3.4.10-4ubuntu1.9+esm3

Get expanded security coverage with Ubuntu Pro

Reduce your average CVE exposure time from 98 days to 1 day with expanded CVE patching, ten-years security maintenance and optional support for the full stack of open-source applications. Free for personal use.

Get Ubuntu Pro 30-day free trial

Patch details

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

Package	Patch details
gnutls28	Upstream: f01e214 Upstream: f341441

Severity score breakdown

CVSS version: CVSS v3.0

Base score 7.5 · High

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	None
Integrity impact	None
Availability impact	High

Scores

Parameter	Value
Base score	7.5 · High
Exploitability score	-
Impact score	-

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Related Ubuntu Security Notices (USN)

USN-8284-1
GnuTLS vulnerabilities
20 May 2026

USN-8502-1
GnuTLS vulnerabilities
6 July 2026