Vulnerability in Rack
CVE-2026-125108
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 .
CVSS v3 metric
CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Rack — versions < 2.2.25, >= 3.0, < 3.1.23, >= 3.2, < 3.2.8
Weakness classification (CWE)
References
- https://github.com/rack/rack/security/advisories/GHSA-p8x9-v4hv-2w4g
- https://github.com/rack/rack/commit/19a1a19cb4da97d61c8d5effeb2e927c44370ae9
- https://github.com/rack/rack/commit/a29512324265790a5536b830490075d0d79323be
- https://github.com/rack/rack/commit/d5e928b803da30b8e40171dbd4be39bed7daa6fa
- https://github.com/rack/rack/releases/tag/v2.2.25
- https://github.com/rack/rack/releases/tag/v3.1.23
- https://github.com/rack/rack/releases/tag/v3.2.8
Frequently asked questions
- What is CVE-2026-125108?
- CVE-2026-125108 is a low-severity vulnerability in Rack, classified under CWE-436. CVSS score: 3.7/10. Published 2026-11-09.
- How severe is CVE-2026-125108?
- Low severity. CVSS v3 base score is 3.7 out of 10.