--- id: CVE-2025-4476 title: >- A denial-of-service vulnerability has been identified in the libsoup HTTP client library 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 wit… severity: medium cvss: 4.3 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L' cwe: - CWE-476 published: '2025-05-16' updated: '2026-06-25' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-4476' references: - url: 'https://access.redhat.com/security/cve/CVE-2025-4476' label: secalert@redhat.com - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2366513' label: secalert@redhat.com - url: 'https://gitlab.gnome.org/GNOME/libsoup/-/issues/440' label: secalert@redhat.com - url: 'https://gitlab.gnome.org/GNOME/libsoup/-/work_items/440' label: 134c704f-9b21-4f2e-91b3-4a467353bcc0 tags: - nvd - exploit-available epss: 0.00385 epssPercentile: 0.32411 ingestedAt: '2026-06-29T13:24:34.207Z' exploits: github: 1 githubRepos: - 'https://github.com/soltanali0/CVE-2025-4476-Exploit' checkedAt: '2026-09-24T07:52:53.428Z' exploitAvailable: true --- ## Overview 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. ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges.