GHSA-r995-q44h-hr64

Ruby WEBrick read_headers method can lead to HTTP Request/Response Smuggling

Source: GitHub Advisory Database (reviewed) Moderate CVE-2025-6442

Packages

Ecosystem	Package	Affected	Fixed in
RubyGems	webrick	< 1.8.2	1.8.2

Details

As written in the advisory (Markdown source, shown as plain text).

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.

References

External links from the advisory. They lead to third-party sites.

https://nvd.nist.gov/vuln/detail/CVE-2025-6442 advisory
https://github.com/ruby/webrick/commit/ee60354bcb84ec33b9245e1d1aa6e1f7e8132101#diff-ad02984d873efb089aa51551bc6b7d307a53e0ba1ac439e91d69c2e… web
https://github.com/ruby/webrick package
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/webrick/CVE-2025-6442.yml web
https://www.zerodayinitiative.com/advisories/ZDI-25-414 web