---
id: CVE-2026-1801
title: 'Libsoup: libsoup: http request smuggling via malformed chunk headers'
summary: >-
  A flaw was found in libsoup, an HTTP client/server library. This HTTP Request
  Smuggling vulnerability arises from non-RFC-compliant parsing in the
  soup_filter_input_stream_read_line() logic, where libsoup accepts malformed
  chunk headers,…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'
cvssSource: cna
cwe:
  - CWE-444
vendor: Red Hat
product: libsoup3
affected:
  - libsoup3 (all versions)
  - libsoup (all versions)
  - libsoup (all versions)
  - libsoup (all versions)
  - libsoup (all versions)
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-02-03T20:40:42.165392Z'
exploitAvailable: true
published: '2026-02-03'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T18:05:30.499Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-1801'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-1801'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2436315'
    label: RHBZ#2436315
  - url: 'https://gitlab.gnome.org/GNOME/libsoup/-/issues/481'
tags:
  - cve.org
  - exploit-available
epss: 0.00421
epssPercentile: 0.36696
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/misterdengi/CVE-2026-1801C'
  checkedAt: '2026-11-07T18:10:19.397Z'
ingestedAt: '2026-11-06T19:01:36.642Z'
---

## Overview

A flaw was found in libsoup, an HTTP client/server library. This HTTP Request Smuggling vulnerability arises from non-RFC-compliant parsing in the soup_filter_input_stream_read_line() logic, where libsoup accepts malformed chunk headers, such as lone line feed (LF) characters instead of the required carriage return and line feed (CRLF). A remote attacker can exploit this without authentication or user interaction by sending specially crafted chunked requests. This allows libsoup to parse and process multiple HTTP requests from a single network message, potentially leading to information disclosure.

## Affected

- `libsoup3 (all versions)`
- `libsoup (all versions)`
- `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 don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.