Description
Rack is a modular Ruby web server interface. Prior to 2.2.25, 3.1.23, and 3.2.8, Rack::Multipart::Parser.parse_boundary can skip a leading empty or quoted boundary parameter in a multipart Content-Type header and accept a later parameter. Rack can therefore parse a request body with a boundary that a conforming intermediary would not derive, allowing form fields or file uploads to reach an application without the intended proxy or web application firewall inspection. This issue is fixed in versions 2.2.25, 3.1.23, and 3.2.8.
Published: 2026-11-09
Score: 3.7 Low
EPSS: < 1% Very Low
KEV: No
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Remediation

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-p8x9-v4hv-2w4g Rack: Multipart boundary ambiguity guard in Rack::Multipart::Parser can be bypassed with a quoted boundary value, allowing WAF bypass
History

Wed, 11 Nov 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-444
References
Metrics threat_severity

None

threat_severity

Low


Mon, 09 Nov 2026 23:45:00 +0000

Type Values Removed Values Added
First Time appeared Rack
Rack rack
Vendors & Products Rack
Rack rack

Mon, 09 Nov 2026 22:15:00 +0000

Type Values Removed Values Added
Description Rack is a modular Ruby web server interface. Prior to 2.2.25, 3.1.23, and 3.2.8, Rack::Multipart::Parser.parse_boundary can skip a leading empty or quoted boundary parameter in a multipart Content-Type header and accept a later parameter. Rack can therefore parse a request body with a boundary that a conforming intermediary would not derive, allowing form fields or file uploads to reach an application without the intended proxy or web application firewall inspection. This issue is fixed in versions 2.2.25, 3.1.23, and 3.2.8.
Title Rack: Multipart boundary ambiguity guard in Rack::Multipart::Parser can be bypassed with a quoted boundary value, allowing WAF bypass
Weaknesses CWE-436
References
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-11-09T21:55:20.600Z

Reserved: 2026-11-09T17:45:35.935Z

Link: CVE-2026-125108

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-09T22:18:41.963

Modified: 2026-11-09T22:18:41.963

Link: CVE-2026-125108

cve-icon Redhat

Severity : Low

Publid Date: 2026-11-09T21:55:20Z

Links: CVE-2026-125108 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-11-09T23:30:18Z

Weaknesses