CVE-2026-126358 Hono: RegExpRouter skips wildcard middleware for some route sets and for paths with an encoded line terminator
Unauthenticated clients can reach route handlers or not-found handlers without wildcard middleware in Hono apps using RegExpRouter with certain patterns.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Harmful if only installed
- No
- Needs a specific call
- Yes
- Fix
- Available
What is CVE-2026-126358?
CVE-2026-126358 is a medium-severity authentication bypass vulnerability in honojs hono, published on 12 Nov 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Hono is a Web application framework that provides support for any JavaScript runtime. From 4.1.4 until 4.13.16, RegExpRouter can omit wildcard middleware in three version-specific cases: since 4.13.0, middleware using the explicit default parameter pattern in /api/:tenant{[^/]+}/admin/* is not applied to a route written as /api/:tenant/admin/:id; since 4.1.4, middleware on /admin/* is not applied to a route registered as /admin* for paths under /admin/; and since 4.4.0, a request path containing an encoded line terminator can reach the not-found handler without wildcard middleware. The default SmartRouter selects RegExpRouter for most applications, and the router's registration-time coverage calculation treated the first two matching pattern pairs as different while its compiled wildcard did not match line terminators in the third case. An unauthenticated client can reach a route handler or the not-found handler without authentication or authorization middleware registered on the wildcard path. TrieRouter, LinearRouter, and PatternRouter apply the middleware in the three described cases. This issue is fixed in version 4.13.16.
Weakness: CWE-863
Which versions are affected by CVE-2026-126358?
1 open source package ship an affected version, including hono.
An affected version is only exploitable if your software calls RegExpRouter. Many projects that include it are not exposed.
| Package | Affected | Fixed in |
|---|---|---|
hono npm | From 4.1.4 | 4.13.16 |
How do I fix CVE-2026-126358?
Upgrade hono to 4.13.16 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-126358 being exploited?
There is no known exploitation of CVE-2026-126358 in the wild and no public exploit code.
Sources
Also known as GHSA-h7mg-cq63-vhpq.