CVE-2026-34230

ruby-rack: Rack is a modular Ruby web server interface

CVE-2026-34230 is fixed in 2 products on 1 platform, first by ruby-rack 3.2.4-1ubuntu1.1, released April 2, 2026. It is not reported as exploited. Patch Radar priority: High.

High
CVSS
7.5
high
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0045
39th percentile

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.

Where it's fixed

ProductFixed inFixReleased
Linux
rmt-server · opensuse-leap 16.0 3.1.0-160000.1.1 OPENSUSE-SU-2026:21640-1 Aug 25, 2026
rmt-server · sles 15.6 2.27-150500.3.47.1 SUSE-SU-2026:2487-1 Jun 22, 2026
rmt-server · sles 16.0 3.1.0-160000.1.1 SUSE-SU-2026:23321-1 Aug 25, 2026
ruby-rack · Debian 12.15 (bookworm) 2.2.22-0+deb12u2 DEBIAN-CVE-2026-34230 Apr 2, 2026
ruby-rack · Debian 13.5 (trixie) 3.1.20-0+deb13u2 DEBIAN-CVE-2026-34230 Apr 2, 2026
ruby-rack · Debian 14 3.2.6-2 DEBIAN-CVE-2026-34230 Apr 2, 2026
ruby-rack · Ubuntu 18.04.6 LTS (bionic) 1.6.4-4ubuntu0.2+esm10 ruby-rack 1.6.4-4ubuntu0.2+esm10 Apr 30, 2026
ruby-rack · Ubuntu 22.04.1 LTS (jammy) 2.1.4-5ubuntu1.2+esm3 ruby-rack 2.1.4-5ubuntu1.2+esm3 Apr 30, 2026
ruby-rack · Ubuntu 24.04.5 LTS (noble) 2.2.7-1ubuntu0.7 ruby-rack 2.2.7-1ubuntu0.7 Apr 30, 2026
ruby-rack · Ubuntu 25.10 (questing) 3.1.16-0.1ubuntu0.3 ruby-rack 3.1.16-0.1ubuntu0.3 Apr 30, 2026
ruby-rack · Ubuntu 26.04.1 LTS (resolute) 3.2.4-1ubuntu1.1 ruby-rack 3.2.4-1ubuntu1.1 Apr 2, 2026

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