Review reviewHigh

CVE-2026-34826

rack

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 proc...

CVSS: 7.5
EPSS: 0.38%
CISA KEV: Not listed
Published: 2026.04.03

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.38%

Technical severityCVSS 7.5

Vulnerability overview

Affected product and versions

Product: rack
Affected versions: >= < 2.2.23, >= >= 3.0.0.beta1, < 3.1.21, >= >= 3.2.0, < 3.2.6, < 2.2.23, >= 3.0.0 < 3.1.21, >= 3.2.0 < 3.2.6
Fixed versions: 2.2.23, 3.1.21, 3.2.6

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that rack and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE: CWE-400, CWE-770