AUGUST 4, 2026
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Case File

CVE-2026-26961

LOW · CVSS 3.7 EPSS 0.25% Public Exploit

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

CyberRota Analysis

This is a low severity vulnerability with a CVSS score of 3.7. Public exploit code or proof-of-concept references have been detected in its references.

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-2026-26961
Severity
LOW
CVSS
3.7
EPSS
0.25%

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::Multipart::Parser extracts the boundary parameter from multipart/form-data using a greedy regular expression. When a Content-Type header contains multiple boundary parameters, Rack selects the last one rather than the first. In deployments where an upstream proxy, WAF, or intermediary interprets the first boundary parameter, this mismatch can allow an attacker to smuggle multipart content past upstream inspection and have Rack parse a different body structure than the intermediary validated. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

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