CVE-2026-34829
rack: Rack: Denial of Service via unbounded multipart file upload
Severity
ImportantRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · April 3, 2026
Updated · November 5, 2026
Description
A flaw was found in Rack. An unauthenticated attacker can exploit this by sending a multipart/form-data request without a Content-Length header. This allows multipart parsing to continue without a total size limit, writing uploaded file parts directly to temporary files on disk. This unbounded disk space consumption leads to a Denial of Service (DoS) condition for Rack applications that accept 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 · 7.5CVSS: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