CVE-2026-47676

MEDIUM

Hono: app.mount() strips mount prefix using undecoded path, causing incorrect routing for percent-encoded paths

Title source: cna
STIX 2.1

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.

References (1)

Core 1
Core References

Scores

CVSS v3 5.3
EPSS 0.0005
EPSS Percentile 15.4%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-444 CWE-693
Status published
Products (2)
hono/hono < 4.12.21
honojs/hono < 4.12.21
Published May 28, 2026
Tracked Since May 28, 2026