CVE-2025-14523: A flaw in libsoup’s HTTP header handling allows multiple Host: headers in a request and returns the last occurrence for server-side processing. Common...

Description

A flaw in libsoup’s HTTP header handling allows multiple Host: headers in a request and returns the last occurrence for server-side processing. Common front proxies often honor the first Host: header, so this mismatch can cause vhost confusion where a proxy routes a request to one backend but the backend interprets it as destined for another host. This discrepancy enables request-smuggling style attacks, cache poisoning, or bypassing host-based access controls when an attacker supplies duplicate Host headers.

Metrics

CVSS 3.1

8.2/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N

EPSS Probability

0.50%

38.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-444

References

Timeline

Published: Dec 11, 2025
Last Modified: Jun 25, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2025-14523?

A flaw in libsoup’s HTTP header handling allows multiple Host: headers in a request and returns the last occurrence for server-side processing. Common front proxies often honor the first Host: header, so this mismatch can cause vhost confusion where a proxy routes a request to one backend but the backend interprets it as destined for another host. This discrepancy enables request-smuggling style attacks, cache poisoning, or bypassing host-based access controls when an attacker supplies duplicate Host headers.

How severe is CVE-2025-14523?

CVE-2025-14523 has a CVSS score of 8.2/10 (HIGH severity). The EPSS model estimates a 0.50% probability of exploitation in the next 30 days.

How do I fix CVE-2025-14523?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.