VDB
CVE-2026-34230
CVE-2026-34230
PUBLISHED
CVSS 5.3 MEDIUM
Reported by GitHub_M · Published April 2, 2026
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.
EPSS 0.02% · 6.6th percentile
Risk Scores
CVSS v3.1
5.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS Score
0.02%
6.6th percentile
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| rack | rack | < 2.2.23, >= 3.0.0.beta1, < 3.1.21, >= 3.2.0, < 3.2.6 |
| rack | rack | >= 3.2.0, < 3.2.6, *, * |
Timeline
- Apr 2, 2026 CVE Published
- Apr 2, 2026 CVE Updated
- Apr 3, 2026 Security Advisory
- May 18, 2026 EPSS Score
- May 19, 2026 EPSS Score
- May 20, 2026 EPSS Score
- May 21, 2026 EPSS Score
- May 22, 2026 EPSS Score
- May 23, 2026 EPSS Score
- May 24, 2026 EPSS Score
- May 25, 2026 EPSS Score
- May 26, 2026 EPSS Score
References
- https://github.com/rack/rack/security/advisories/GHSA-v569-hp3g-36wr x_refsource_CONFIRM