CVE-2026-126356
Hono: `validator('form')` skips validation for `multipart/form-data` requests with extra parameters
Hono is a Web application framework that provides support for any JavaScript runtime. From 4.5.1 until 4.13.16, validator('form') uses a strict whole-header pattern that fails to recognize multipart/form-data when its Content-Type includes another legal parameter or extra whitespace after a semicolon. The validation callback receives an empty object even though c.req.parseBody() or c.req.formData() can still parse and expose all submitted fields to the handler. An unauthenticated client can therefore bypass allow-list or required-field checks when the application relies on the form validator and its callback accepts an empty object. application/x-www-form-urlencoded requests are not affected. This issue is fixed in version 4.13.16.
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 |
|---|---|---|
| hono honojs |
>= 4.5.1, < 4.13.16 (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 / 5.3 medium |
CVSS:3.1/AV:N/AC:L/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/honojs/hono/security/advisories/GHSA-4h7h-rv7c-7m2vCNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/honojs/hono/commit/d88fab372415277a9e540e895650943dd08eef4aCNA: GitHub_M · x_refsource_MISC
- https://github.com/honojs/hono/releases/tag/v4.13.16CNA: GitHub_M · x_refsource_MISC
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