CVE-2025-6442
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2025-6442
Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2025-6442.html
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| sles | affected | | |
| debian | bookworm | affected | |
| debian | forky | fixed | 1.9.1-1 |
| debian | sid | fixed | 1.9.1-1 |
| debian | trixie | fixed | 1.9.1-1 |
References
- https://github.com/advisories/GHSA-r995-q44h-hr64
- https://www.suse.com/security/cve/CVE-2025-6442.html
- https://nvd.nist.gov/vuln/detail/CVE-2025-6442
- https://github.com/ruby/webrick/commit/ee60354bcb84ec33b9245e1d1aa6e1f7e8132101#diff-ad02984d873efb089aa51551bc6b7d307a53e0ba1ac439e91d69c2e58a478864
- https://github.com/ruby/webrick
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/webrick/CVE-2025-6442.yml
- https://www.zerodayinitiative.com/advisories/ZDI-25-414
- https://security-tracker.debian.org/tracker/CVE-2025-6442
Verify integrity in audit chain (admin only). AS-IS.