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Fencer Vulns
medium 4.3

CVE-2025-4476 json

Libsoup: null pointer dereference in libsoup may lead to denial of service

published 2025-05-16 17 mo ago modified 2026-11-06 2 d ago also EUVD-2025-15540

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 46%
public exploits
0
none known

Summary

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.

Patch / fix

  • libsoup3 Debian 13 3.6.5-2

debian advisories DEBIAN-CVE-2025-4476

  • libsoup3 Ubuntu 24.04 LTS 3.4.4-5ubuntu0.4
  • libsoup2.4 Ubuntu 20.04 LTS 2.70.0-1ubuntu0.5
  • libsoup2.4 Ubuntu 22.04 LTS 2.74.2-3ubuntu0.5
  • libsoup2.4 Ubuntu 24.04 LTS 2.74.3-6ubuntu1.5
  • libsoup3 Ubuntu Pro 22.04 LTS 3.0.7-0ubuntu1+esm4
  • libsoup2.4 Ubuntu Pro 16.04 LTS 2.52.2-1ubuntu0.3+esm3
  • libsoup2.4 Ubuntu Pro 18.04 LTS 2.62.1-1ubuntu0.4+esm4

ubuntu advisories UBUNTU-CVE-2025-4476

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libsoup2 SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Basesystem 15 SP7 +1 more 2.74.3-150600.4.24.1
  • libsoup2 SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +8 more 2.74.2-150400.3.26.1
  • libsoup SLE Micro 5.2 2.68.4-150200.4.27.1
  • libsoup Linux Micro 6.1 3.4.4-slfo.1.1_4.1
  • libsoup Linux Micro 6.0 3.4.2-8.1
  • libsoup SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +7 more 3.0.4-150400.3.10.1
  • libsoup SLE Module for Basesystem 15 SP7, SLE Module for Basesystem 15 SP6, openSUSE Leap 15.6 3.4.4-150600.3.10.1
  • libsoup SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.62.2-5.34.1

suse advisories SUSE-SU-2026:0703-1SUSE-SU-2026:0574-1SUSE-SU-2026:0497-1SUSE-SU-2026:0469-1SUSE-SU-2025:20598-1SUSE-SU-2025:20453-1

  • libsoup2 openSUSE Leap 16.0 2.74.3-160000.4.1
  • libsoup2 openSUSE Tumbleweed 2.74.3-15.1
  • libsoup openSUSE Tumbleweed 3.6.5-5.1

opensuse advisories openSUSE-SU-2026:20354-1openSUSE-SU-2026:10166-1openSUSE-SU-2025:15185-1

  • libsoup CBL-Mariner 2.0 3.0.4-7
  • libsoup Azure Linux 3.0 3.4.4-7

azure linux advisories AZL-61902AZL-61910

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-4476 updated cvss 4.3

libsoup: Null pointer dereference in libsoup may lead to Denial Of Service

  • Red Hat Enterprise Linux 6 libsoup Red Hat Enterprise Linux 7 libsoup
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 libsoup Red Hat Enterprise Linux 9 libsoup Red Hat Enterprise Linux 10 libsoup3
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

0.55% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • gitlab.gnome.org https://gitlab.gnome.org/GNOME/libsoup/-/work_items/440 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.