---
id: CVE-2026-4271
title: 'Libsoup: libsoup: denial of service via use-after-free in http/2 server'
summary: >-
  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…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cvssSource: cna
cwe:
  - CWE-416
vendor: Red Hat
product: libsoup3
affected:
  - libsoup3 (all versions)
  - libsoup3 (all versions)
  - libsoup3 (all versions)
  - libsoup (all versions)
  - libsoup
  - libsoup
  - libsoup
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-03-17T13:04:24.452812Z'
exploitAvailable: true
published: '2026-03-17'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T20:46:36.340Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-4271'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:15968'
    label: 'RHSA-2026:15968'
  - url: 'https://access.redhat.com/errata/RHSA-2026:17482'
    label: 'RHSA-2026:17482'
  - url: 'https://access.redhat.com/errata/RHSA-2026:19143'
    label: 'RHSA-2026:19143'
  - url: 'https://access.redhat.com/security/cve/CVE-2026-4271'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2448044'
    label: RHBZ#2448044
  - url: 'https://gitlab.gnome.org/GNOME/libsoup/-/issues/496'
tags:
  - cve.org
  - exploit-available
epss: 0.0088
epssPercentile: 0.59257
ingestedAt: '2026-11-05T22:38:31.880Z'
---

## Overview

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).

## Affected

- `libsoup3 (all versions)`
- `libsoup3 (all versions)`
- `libsoup3 (all versions)`
- `libsoup (all versions)`
- `libsoup`
- `libsoup`
- `libsoup`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

### Workarounds

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.