CVEvulnerability

CVE-2026-34827

7.5 HIGH Published 2026-04-02 Modified 2026-07-24 Official page ↗
Status
Modified
Published
2026-04-02
Last modified
2026-07-24
Assigner
[email protected]
CVSS 3.1 ([email protected])
7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1 (0b0ca135-0b70-47e7-9f44-1890c2a1c46c)
7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weaknesses
CWE-400, CWE-407, CWE-770

Description

Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21, and 3.2.0 to before 3.2.6, Rack::Multipart::Parser#handle_mime_head parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated String#index searches combined with String#slice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An unauthenticated attacker can send a crafted multipart/form-data request containing many parts with long backslash-escaped parameter values to trigger excessive CPU usage during multipart parsing. This results in a denial of service condition in Rack applications that accept multipart form data. This issue has been patched in versions 3.1.21 and 3.2.6.

Affected configurations

• rack rack (>= 3.0.0 < 3.1.21) • rack rack (>= 3.2.0 < 3.2.6)

Related

Weakness · CWE (3)

  • CWE-400 Uncontrolled Resource Consumption weakness
  • CWE-407 Inefficient Algorithmic Complexity weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling weakness

References