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Rack CVE-2026-26962

| EUVD-2026-18417 MEDIUM
Improper Neutralization of CRLF Sequences ('CRLF Injection') (CWE-93)
2026-04-02 GitHub_M GHSA-rx22-g9mx-qrhv
4.8
CVSS 3.1
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CVSS VectorNVD

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

Lifecycle Timeline

4
Patch released
Apr 03, 2026 - 02:30 nvd
Patch available
EUVD ID Assigned
Apr 02, 2026 - 17:30 euvd
EUVD-2026-18417
Analysis Generated
Apr 02, 2026 - 17:30 vuln.today
CVE Published
Apr 02, 2026 - 17:10 nvd
MEDIUM 4.8

DescriptionNVD

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.

AnalysisAI

Rack versions 3.2.0 through 3.2.5 fail to properly unfold folded multipart headers containing obs-fold sequences, preserving embedded CRLF characters in parsed parameter values like filename and name. This allows unauthenticated remote attackers with high request complexity to inject HTTP response headers or split responses when applications reuse these parsed values, leading to potential session hijacking, cache poisoning, or credential theft. …

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CVE-2026-26962 vulnerability details – vuln.today

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