Rack: Quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encoding header (rack rack)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.45 % · percentile 39 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
Description
Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Utils.select_best_encoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard (*) entries. Because this method is used by Rack::Deflater to choose a response encoding, an unauthenticated attacker can send a single request with a crafted Accept-Encoding header and cause disproportionate CPU consumption on the compression middleware path. This results in a denial of service condition for applications using Rack::Deflater. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.
Weaknesses (CWE)
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L | GitHub_M |
| CVSS 3.1 | MEDIUM 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L | NVD · security-advisories@github.com (Secondary) |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD · nvd@nist.gov (Primary) |
Advisories
- GHSA-v569-hp3g-36wr — Rack has quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encoding header
European references
- ENISA EUVD · EUVD-2026-18378
- GCVE · GCVE-0-2026-34230
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:*:*< 2.2.23cpe: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 < 2.2.23 ; 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 |