MEDIUM6.5

GHSA-r995-q44h-hr64

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

Quick fix

GHSA-r995-q44h-hr64 — webrick: upgrade to the fixed version with the command below.

bundle update webrick

Details

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.

Are you affected?

Enter the version of the package you're using.

Affected packages

RubyGems/webrick

Introduced in: 0Fixed in: 1.8.2

Fixbundle update webrick

References

https://nvd.nist.gov/vuln/detail/CVE-2025-6442[ADVISORY]
https://github.com/ruby/webrick/commit/ee60354bcb84ec33b9245e1d1aa6e1f7e8132101#diff-ad02984d873efb089aa51551bc6b7d307a53e0ba1ac439e91d69c2e58a478864[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]