HTTP Host Header Smuggling via libsoups Duplicate Host Handling
CVE-2025-14523 Published on December 11, 2025

Libsoup: libsoup: duplicate host header handling causes host-parsing discrepancy (first- vs last-value wins)
A flaw in libsoups 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.

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Vulnerability Analysis

CVE-2025-14523 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a high impact on integrity, and no impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
LOW
Integrity Impact:
HIGH
Availability Impact:
NONE

Timeline

Reported to Red Hat.

Made public.

Weakness Type

What is a HTTP Request Smuggling Vulnerability?

When malformed or abnormal HTTP requests are interpreted by one or more entities in the data flow between the user and the web server, such as a proxy or firewall, they can be interpreted inconsistently, allowing the attacker to "smuggle" a request to one device without the other device being aware of it.

CVE-2025-14523 has been classified to as a HTTP Request Smuggling vulnerability or weakness.


Products Associated with CVE-2025-14523

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2025-14523 are published in these products:

Red Hat Enterprise Linux (RHEL)
 
Red Hat Enterprise Linux Eus
 
Red Hat Rhel Tus
 
Red Hat Rhel E4s
 
Red Hat Rhel Aus
 
Red Hat Rhel Eus
 
Red Hat Rhel Eus Long Life
 
Red Hat Rhel Els
 

Affected Versions

Red Hat Enterprise Linux 10: Red Hat Enterprise Linux 10.0 Extended Update Support: Red Hat Enterprise Linux 7 Extended Lifecycle Support: Red Hat Enterprise Linux 8: Red Hat Enterprise Linux 8: Red Hat Enterprise Linux 8: Red Hat Enterprise Linux 8.2 Advanced Update Support: Red Hat Enterprise Linux 8.2 Advanced Update Support: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support: Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On: Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On: Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support: Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support: Red Hat Enterprise Linux 8.6 Telecommunications Update Service: Red Hat Enterprise Linux 8.6 Telecommunications Update Service: Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions: Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions: Red Hat Enterprise Linux 8.8 Telecommunications Update Service: Red Hat Enterprise Linux 8.8 Telecommunications Update Service: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions: Red Hat Enterprise Linux 9: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions: Red Hat Enterprise Linux 9.4 Extended Update Support: Red Hat Enterprise Linux 9.6 Extended Update Support: Red Hat Enterprise Linux 6:

Exploit Probability

EPSS
0.02%
Percentile
4.04%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.