Rack: Forwarded Header semicolon injection enables Host and Scheme spoofing (rack rack)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.19 % · percentile 8 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
Description
Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21 and 3.2.0 to before 3.2.6, Rack::Utils.forwarded_values parses the RFC 7239 Forwarded header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header can be interpreted by Rack as multiple Forwarded directives rather than as a single quoted for value. In deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted Forwarded values differently, this discrepancy can allow an attacker to smuggle host, proto, for, or by parameters through a single header value. This issue has been patched in versions 3.1.21 and 3.2.6.
Weaknesses (CWE)
- CWE-436 — Interpretation Conflict
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 4.8 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N | GitHub_M |
| CVSS 3.1 | MEDIUM 4.8 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N | NVD · security-advisories@github.com (Secondary) |
| CVSS 3.1 | MEDIUM 6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N | NVD · nvd@nist.gov (Primary) |
Advisories
- GHSA-qfgr-crr9-7r49 — Rack: Forwarded Header semicolon injection enables Host and Scheme spoofing
European references
- ENISA EUVD · EUVD-2026-18423
- GCVE · GCVE-0-2026-32762
CERT-FR advisories
- CERTFR-2026-AVI-1352 — Multiples vulnérabilités dans Oracle PeopleSoft · cert.ssi.gouv.fr
Affected configurations (NVD CPE)
cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*≥ 3.0.0 < 3.1.21cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*≥ 3.2.0 < 3.2.6
Affected products
| Product | Versions |
|---|---|
| rack · rack | affected >= 3.0.0.beta1, < 3.1.21 ; affected >= 3.2.0, < 3.2.6 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |