CVE Database›Document archive›CVE-2026-34827

CVE-2026-34827

rack: Rack: Denial of Service via crafted multipart/form-data requests

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Severity

Important

Red Hat Product Security

7.5

CVSS 3.1

Review impact separately from score.

Published · April 3, 2026

Updated · November 5, 2026

Description

A flaw was found in Rack, a modular Ruby web server interface. An unauthenticated attacker can exploit this vulnerability by sending a specially crafted multipart/form-data request. This request, containing numerous parts with lengthy backslash-escaped parameter values, causes the system to consume excessive CPU resources during parsing. This algorithmic complexity issue ultimately leads to a denial of service (DoS) condition in Rack applications that process multipart form data.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

CVSS / CWE

CVSS 3.1 · 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE-770 · Allocation of Resources Without Limits or Throttling