CVE-2025-6442

Ruby WEBrick read_header HTTP Request Smuggling Vulnerability

Published Jun 25, 2025 CVSS 3.1 · 5.9 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2025-19113 Ruby WEBrick read_headers method can lead to HTTP Request/Response Smuggling
Github GHSA Github GHSA GHSA-r995-q44h-hr64 Ruby WEBrick read_headers method can lead to HTTP Request/Response Smuggling
Ubuntu USN Ubuntu USN USN-7709-1 WEBrick vulnerability
Ubuntu USN Ubuntu USN USN-7840-1 Ruby vulnerabilities
History
Type Values Removed Values Added
First Time appeared Ruby-lang
Ruby-lang webrick
CPEs cpe:2.3:a:ruby-lang:webrick:*:*:*:*:*:ruby:*:*
Vendors & Products Ruby-lang
Ruby-lang webrick
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N'}

Type Values Removed Values Added
Metrics epss

{'score': 0.00066}

epss

{'score': 0.00049}

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Ruby WEBrick read_header HTTP Request Smuggling Vulnerability
Weaknesses CWE-444
References
Metrics cvssV3_0

{'score': 6.5, 'vector': 'CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
zdi
Published
Updated
Jun 25, 2025, 8:42 PM
Reserved
Jun 20, 2025, 5:14 PM
Status
Analyzed
Published
Jun 25, 2025, 5:15 PM
Modified
Jun 17, 2026, 10:01 AM
Severity
Moderate
Public date
Jun 25, 2025, 4:52 PM