---
id: CVE-2026-3633
title: 'Libsoup: libsoup: header and http request injection via crlf injection'
summary: >-
  A flaw was found in libsoup. A remote attacker, by controlling the method
  parameter of the `soup_message_new()` function, could inject arbitrary headers
  and additional request data. This vulnerability, known as CRLF (Carriage
  Return Line…
severity: low
cvss: 3.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:L'
cvssSource: cna
cwe:
  - CWE-93
vendor: Red Hat
product: libsoup3
affected:
  - libsoup3 (all versions)
  - libsoup
  - libsoup (all versions)
  - libsoup (all versions)
  - libsoup (all versions)
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-03-17T12:59:46.420116Z'
published: '2026-03-17'
updated: '2026-11-03'
sourceUpdated: '2026-11-03T04:04:44.469Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-3633'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-3633'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2445128'
    label: RHBZ#2445128
  - url: 'https://gitlab.gnome.org/GNOME/libsoup/-/issues/484'
tags:
  - cve.org
epss: 0.00237
epssPercentile: 0.14871
ingestedAt: '2026-11-05T19:30:42.889Z'
---

## Overview

A flaw was found in libsoup. A remote attacker, by controlling the method parameter of the `soup_message_new()` function, could inject arbitrary headers and additional request data. This vulnerability, known as CRLF (Carriage Return Line Feed) injection, occurs because the method value is not properly escaped during request line construction, potentially leading to HTTP request injection.

## Affected

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

## 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 do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.