CVE-2026-126356
Hono: `validator('form')` skips validation for `multipart/form-data` requests with extra parameters
Description
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.
INFO
Published Date :
Nov. 13, 2026, 12:20 a.m.
Last Modified :
Nov. 13, 2026, 2:18 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | MITRE-CVE | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Hono to version 4.13.16 or later.
- Ensure Content-Type validation handles multipart/form-data correctly.
- Review access controls for sensitive operations.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-126356.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-126356 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-126356
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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The following list is the news that have been mention
CVE-2026-126356 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-126356 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Nov. 13, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-126356', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-11-13T00:36:28.247312Z'} -
New CVE Received by [email protected]
Nov. 13, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Added CWE CWE-20 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/126xxx/CVE-2026-126356.json">CVE-2026-126356</a> Added Reference https://github.com/honojs/hono/commit/d88fab372415277a9e540e895650943dd08eef4a Added Reference https://github.com/honojs/hono/releases/tag/v4.13.16 Added Reference https://github.com/honojs/hono/security/advisories/GHSA-4h7h-rv7c-7m2v