CVE-2026-47676 Details
Description
Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, app.mount() strips the mount prefix from the incoming request path using the raw URL pathname, while route matching is performed against the percent-decoded path. This inconsistency causes the prefix to be stripped at the wrong position when the path contains percent-encoded multi-byte characters, resulting in the mounted sub-application receiving an incorrect path. This vulnerability is fixed in 4.12.21.
A routing vulnerability exists in the Hono web application framework for JavaScript runtimes, affecting versions prior to 4.12.21. The issue arises in the app.mount() function, which incorrectly strips the mount prefix from request paths that include percent-encoded multi-byte characters. This mismatch causes mounted sub-applications to receive garbled or partial paths, disrupting the intended routing. The vulnerability can lead to middleware or route handlers being bypassed or misrouted, particularly when the request URL contains encoded non-ASCII characters.
Users can upgrade to Hono version 4.12.21 or later to address this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed May 28, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/honojs/hono/security/advisories/GHSA-2gcr-mfcq-wcc3 | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-444 | Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') | [email protected] |
| CWE-693 | Protection Mechanism Failure | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| hono hono | < 4.12.21 |
CPE
Remediation
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Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 29, 2026 | Initial Analysis | [email protected] |
| May 28, 2026 | New CVE Received | [email protected] |