Bug 2454508 (CVE-2026-34826)

Summary: CVE-2026-34826 rack: Rack: Denial of Service via malicious HTTP Range header
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, rhel-process-autobot, tsedmik, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Rack. A remote attacker can exploit this by sending a specially crafted HTTP Range header containing numerous small, overlapping byte ranges. This can cause disproportionate consumption of CPU, memory, I/O, and bandwidth resources. The result is a Denial of Service (DoS) condition in Rack file-serving paths that process multipart byte range responses.
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Description OSIDB Bzimport 2026-04-02 18:02:53 UTC 
Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Utils.get_byte_ranges parses the HTTP Range header without limiting the number of individual byte ranges. Although the existing fix for CVE-2024-26141 rejects ranges whose total byte coverage exceeds the file size, it does not restrict the count of ranges. An attacker can supply many small overlapping ranges such as 0-0,0-0,0-0,... to trigger disproportionate CPU, memory, I/O, and bandwidth consumption per request. This results in a denial of service condition in Rack file-serving paths that process multipart byte range responses. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.