CVE-2026-26961

Published: Apr 02, 2026 Last Modified: Apr 02, 2026
ExploitDB:
Other exploit source:
Google Dorks:
LOW 3,7
Source: [email protected]
Attack Vector: network
Attack Complexity: high
Privileges Required: none
User Interaction: none
Scope: unchanged
Confidentiality: none
Integrity: low
Availability: none

Description

AI Translation Available

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.

436

Interpretation Conflict

Incomplete
Abstraction: Class Structure: Simple
Common Consequences
Security Scopes Affected:
Integrity Other
Potential Impacts:
Unexpected State Varies By Context
Applicable Platforms
All platforms may be affected
View CWE Details
https://github.com/rack/rack/security/advisories/GHSA-vgpv-…
https://github.com/rack/rack/security/advisories/GHSA-vgpv-f759-9wx3