Bug 2454511 (CVE-2026-26962)

Summary: CVE-2026-26962 rack: Rack: Header injection and response splitting via incorrect multipart header parsing
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akostadi, amasferr, crizzo, dmayorov, eshamard, jlledo, jvasik, kaycoth, pantinor, rblanco, tsedmik
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Rack, a modular Ruby web server interface. Rack::Multipart::Parser incorrectly processes folded multipart part headers, failing to remove embedded carriage return and line feed (CRLF) characters. This can lead to applications that reuse these parsed values in HTTP response headers becoming vulnerable to header injection or response splitting, potentially allowing an attacker to manipulate HTTP responses.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-04-02 18:03:03 UTC 
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.