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.
Executive briefing
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Evidence confidence: Not assessed Evidence-derived, not an exploitability verdict
Severity & attack characteristics
CVSS vector:CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Technical explanation & impact
Technical root-cause details are not available in the current source record.
Assess the impact using the published CVSS metrics and the affected vendor component.
Affected products and versions
NVD has not supplied machine-readable vulnerable CPE product/version entries for this CVE. This is an information gap, not proof that no products are affected. Check the vendor advisory references below.
Remediation & validation
- Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
No fixed version is displayed unless it is explicitly established by a vendor advisory. Follow the vendor's release notes for exact product and branch applicability.
Vendor advisories, patches & exploit references
- https://github.com/rack/rack/commit/19a1a19cb4da97d61c8d5effeb2e927c44370ae9 VENDOR security-advisories@github.com
- https://github.com/rack/rack/commit/a29512324265790a5536b830490075d0d79323be VENDOR security-advisories@github.com
- https://github.com/rack/rack/commit/d5e928b803da30b8e40171dbd4be39bed7daa6fa VENDOR security-advisories@github.com
- https://github.com/rack/rack/releases/tag/v2.2.25 VENDOR security-advisories@github.com
- https://github.com/rack/rack/releases/tag/v3.1.23 VENDOR security-advisories@github.com
- https://github.com/rack/rack/releases/tag/v3.2.8 VENDOR security-advisories@github.com
- https://github.com/rack/rack/security/advisories/GHSA-p8x9-v4hv-2w4g VENDOR security-advisories@github.com