Rack up to 2.2.22/3.1.20/3.2.5 Rack::Utils resource consumption

Summaryinfo

A vulnerability, which was classified as problematic, was found in Rack up to 2.2.22/3.1.20/3.2.5. The impacted element is the function Rack::Utils. Such manipulation leads to resource consumption. This vulnerability is traded as CVE-2026-34826. The attack may be launched remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Rack up to 2.2.22/3.1.20/3.2.5. Affected by this issue is the function Rack::Utils. The manipulation with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Impacted is availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-34826 since 03/30/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 2.2.23, 3.1.21 or 3.2.6 eliminates this vulnerability.

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Productinfo

Name

• Rack

Version

• 2.2.0
• 2.2.1
• 2.2.2
• 2.2.3
• 2.2.4
• 2.2.5
• 2.2.6
• 2.2.7
• 2.2.8
• 2.2.9
• 2.2.10
• 2.2.11
• 2.2.12
• 2.2.13
• 2.2.14
• 2.2.15
• 2.2.16
• 2.2.17
• 2.2.18
• 2.2.19
• 2.2.20
• 2.2.21
• 2.2.22
• 3.1.0
• 3.1.1
• 3.1.2
• 3.1.3
• 3.1.4
• 3.1.5
• 3.1.6
• 3.1.7
• 3.1.8
• 3.1.9
• 3.1.10
• 3.1.11
• 3.1.12
• 3.1.13
• 3.1.14
• 3.1.15
• 3.1.16
• 3.1.17
• 3.1.18
• 3.1.19
• 3.1.20
• 3.2.0
• 3.2.1
• 3.2.2
• 3.2.3
• 3.2.4
• 3.2.5

Website

• Product: https://github.com/rack/rack/

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