🛡️ CVE-2025-4476 on Debian — libsoup2.4

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

A denial-of-service vulnerability has been identified in the libsoup HTTP client library. This flaw can be triggered when a libsoup client receives a 401 (Unauthorized) HTTP response containing a specifically crafted domain parameter within the WWW-Authenticate header. Processing this malformed header can lead to a crash of the client application using libsoup. An attacker could exploit this by setting up a malicious HTTP server. If a user's application using the vulnerable libsoup library connects to this malicious server, it could result in a denial-of-service. Successful exploitation requires tricking a user's client application into connecting to the attacker's malicious server.

Distribution advisory

This page covers CVE-2025-4476 as tracked by Debian, for the package libsoup2.4. The fix is available in version 3.6.5-2; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability low.

Weakness class

DEBIAN-CVE-2025-4476 is classified as CWE-476: NULL Pointer Dereference. A pointer that can be null is used without a check, crashing the process.

Affected software

DEBIAN-CVE-2025-4476 is recorded against 2 packages.

  • libsoup2.4
  • libsoup3 (fixed in 3.6.5-2)

Timeline and source

Published on 16 May 2025 and last revised on 4 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

CVE-2025-4476 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2025-05-16
Updated 2026-08-12
Modified 2026-08-04
Fix URL N/A

Affected Packages

Software From version Fixed in
libsoup2.4 — —
libsoup3 — 3.6.5-2

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