Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.

Project Subscriptions

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-rx22-g9mx-qrhv Rack's improper unfolding of folded multipart headers preserves CRLF in parsed parameter values
Fixes

Solution

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Workaround

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History

Thu, 02 Apr 2026 20:30:00 +0000

Type Values Removed Values Added
Description Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.
Title Rack: Header injection in multipart requests
Weaknesses CWE-93
References
Metrics cvssV3_1

{'score': 4.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-04-02T17:10:17.091Z

Reserved: 2026-02-16T22:20:28.612Z

Link: CVE-2026-26962

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-04-02T18:16:26.773

Modified: 2026-04-02T18:16:26.773

Link: CVE-2026-26962

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses