CVE-2026-4271

Publication date 17 March 2026

Last updated 9 July 2026

Ubuntu priority

Cvss 3 Severity Score

Description

A flaw was found in libsoup, a library for handling HTTP requests. This vulnerability, known as a Use-After-Free, occurs in the HTTP/2 server implementation. A remote attacker can exploit this by sending specially crafted HTTP/2 requests that cause authentication failures. This can lead to the application attempting to access memory that has already been freed, potentially causing application instability or crashes, resulting in a Denial of Service (DoS).

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
libsoup2.4	26.04 LTS resolute	Not affected
	25.10 questing	Not affected
	24.04 LTS noble	Not affected
	22.04 LTS jammy	Not affected
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
libsoup3	26.04 LTS resolute	Needs evaluation
	25.10 questing	Ignored end of life, was needs-triage
	24.04 LTS noble	Needs evaluation
	22.04 LTS jammy	Needs evaluation

Notes

mrmajumder

no HTTP/2 server in libsoup2.4

Patch details

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

Package	Patch details
libsoup2.4	Upstream: 489affa

Severity score breakdown

CVSS version: CVSS v3.0

Base score 5.3 · Medium

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	Low

Scores

Parameter	Value
Base score	5.3 · Medium
Exploitability score	-
Impact score	-

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