CVE-2025-6442

MEDIUM EPSS 33.8%
Published Jun 25, 20251y ago · Modified Jun 17, 20261w ago
5.9 CVSS 3.1
Medium
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Published Jun 25, 2025 1y ago
Last Modified Jun 17, 2026 1w ago

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.

CVSS Details

Base Score
5.9
Exploitability
2.2
Impact
3.6
Vector string
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Attack Vector Network
Attack Complexity High
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity High
Availability None

Threat Intelligence

EPSS Exploit Probability
33.8% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-444

Affected Products 1

VendorProductVersionRange
ruby-langwebrick* <1.8.2

References 2

  • github.com https://github.com/ruby/webrick/commit/ee60354bcb84ec33b9245e1d1aa6e1f7e8132101#diff-ad02984d873efb089aa51551bc6b7d307a53e0ba1ac439e91d69c2e58a478864
    Patch
  • zerodayinitiative.com https://www.zerodayinitiative.com/advisories/ZDI-25-414/
    Third Party Advisory

Remediation

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