CVE-2026-34826
MediumCVSS 5.3Exploitation Probability (EPSS)
Low risk31th percentile - higher than 31% of all known CVEs
Summary
Rack before versions 2.2.23, 3.1.21, and 3.2.6 has a denial of service vulnerability due to an unlimited number of byte ranges in the HTTP Range header. An attacker can supply many small overlapping ranges, causing disproportionate CPU, memory, I/O, and bandwidth consumption.
Risk Assessment
An attacker can overload the Rack server, causing denial of service for all requests serving files with multipart byte range responses.
Recommendation
Upgrade Rack to version 2.2.23, 3.1.21, or 3.2.6 depending on the branch in use.
Original NVD description (English source)
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.