CVE-2026-34826
Rack's multipart byte range processing allows denial of service via excessive overlapping ranges
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| rubygems | rack | < 2.2.23 | 2.2.23 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Rack | Rack | before 2.2.23 from 3.0.0 before 3.1.21 from 3.2.0 before 3.2.6 |