CVE-2025-6442
Published:June 25, 2025
Updated:June 07, 2026
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 Packages
https://github.com/ruby/webrick.git (GITHUB):
Affected version(s) >=v1.4.0 < v1.8.2Fix Suggestion:
Update to version v1.8.2webrick (RUBY):
Affected version(s) >=1.3.1 <1.8.2Fix Suggestion:
Update to version 1.8.2Related Resources (5)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.3
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.5
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
EPSS
Base Score:
0.26