PT-2026-29809 · Rack · Rack

Kwkr · Published 2026-04-02 · Updated 2026-04-02 · CVE-2026-34230

Mitre

CVSS v3.1

5.3

Medium

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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.

Fix

Resource Exhaustion

Weakness Enumeration

CWE-400

CWE-407

Related Identifiers

CVE-2026-34230

Affected Products

Rack

References · 2

• https://nvd.nist.gov/vuln/detail/CVE-2026-34230 · Security Note
• https://github.com/rack/rack/security/advisories/GHSA-v569-hp3g-36wr · Note