Inconsistent interpretation of HTTP requests in hono - CVE-2026-47676
Published: July 24, 2026
Vulnerability identifier: #VU139277
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-47676
CWE-ID: CWE-444
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to inconsistent interpretation of request paths in app.mount() when processing percent-encoded paths. A remote attacker can send a specially crafted request containing percent-encoded multi-byte characters to disclose sensitive information.
The issue can cause the mounted sub-application to receive an incorrectly stripped path, which may bypass middleware or route matching and reach unintended handlers within the sub-application.
Affected software
hono
How to mitigate CVE-2026-47676
Install security update from vendor's website.
hono - update to 4.12.21