AUGUST 4, 2026
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Case File

CVE-2026-34230

MEDIUM · CVSS 5.3 EPSS 0.43% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2026-04-02 · Last synced 2026-08-04

CyberRota Analysis

This is a medium severity vulnerability with a CVSS score of 5.3. Public exploit code or proof-of-concept references have been detected in its references. Exploitation may require the attacker to be authenticated. It may lead to a denial-of-service condition.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-34230
Severity
MEDIUM
CVSS
5.3
EPSS
0.43%

Original NVD 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.

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