CVE-2025-6442

Published: Jun 25, 2025Modified: Jun 17, 2026

5.9

Vector

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

Exploitability: 2.2 / Impact: 3.6

Source: NVD

Description

Ruby WEBrick read_header HTTP Request Smuggling Vulnerability. This vulnerability allows remote attackers to smuggle arbitrary HTTP requests on affected installations of Ruby WEBrick. This issue is exploitable when the product is deployed behind an HTTP proxy that fulfills specific conditions. The specific flaw exists within the read_headers method. The issue results from the inconsistent parsing of terminators of HTTP headers. An attacker can leverage this vulnerability to smuggle arbitrary HTTP requests. Was ZDI-CAN-21876.

Affected (1)

Products: Ruby Lang: Webrick

1 product

Configuration A

1 vulnerable

Vulnerable Software	Affected Versions
Ruby Lang Webrick	Before 1.8.2

Related CWEs

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

References (2)

https://github.com/ruby/webrick/commit/ee60354bcb84ec33b9245e1d1aa6e1f7e8132101#diff-ad02984d873efb089aa51551bc6b7d307a53e0ba1ac439e91d69c2e58a478864

Source: zdi-disclosures@trendmicro.com

Patch

https://www.zerodayinitiative.com/advisories/ZDI-25-414/

Source: zdi-disclosures@trendmicro.com

Third Party Advisory

Timeline

No history available yet.