CVE-2026-125108
Rack: Multipart boundary ambiguity guard in Rack::Multipart::Parser can be bypassed with a quoted boundary value, allowing WAF bypass
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.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| rack rack |
< 2.2.25 (affected) >= 3.0, < 3.1.23 (affected) >= 3.2, < 3.2.8 (affected) |
CNA: GitHub_M |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 3.7 low |
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N | CNA: GitHub_M |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/rack/rack/security/advisories/GHSA-p8x9-v4hv-2w4gCNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/rack/rack/commit/19a1a19cb4da97d61c8d5effeb2e927c44370ae9CNA: GitHub_M · x_refsource_MISC
- https://github.com/rack/rack/commit/a29512324265790a5536b830490075d0d79323beCNA: GitHub_M · x_refsource_MISC
- https://github.com/rack/rack/commit/d5e928b803da30b8e40171dbd4be39bed7daa6faCNA: GitHub_M · x_refsource_MISC
- https://github.com/rack/rack/releases/tag/v2.2.25CNA: GitHub_M · x_refsource_MISC
- https://github.com/rack/rack/releases/tag/v3.1.23CNA: GitHub_M · x_refsource_MISC
- https://github.com/rack/rack/releases/tag/v3.2.8CNA: GitHub_M · x_refsource_MISC
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