CVE-2026-109955 Hono 4.12.4 before 4.13.11 Middleware Bypass via serveStatic Double Decoding
Attackers can bypass authentication middleware in Hono by exploiting double path decoding in serveStatic, accessing protected static files without credentials.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-109955?
CVE-2026-109955 is a medium-severity authentication bypass vulnerability in honojs hono, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Hono from 4.12.4 before 4.13.11 contains a middleware bypass vulnerability in serveStatic that allows unauthenticated attackers to skip prefix middleware by exploiting double path decoding. Attackers can send malformed percent-encoded paths that the router matches in encoded form, reaching static files without authentication checks running.
Weakness: CWE-174
Which versions are affected by CVE-2026-109955?
Linux distribution packages (2)
grafana13.1 Red Hat:hummingbird:1 | All versions | 0:13.1.7-0.2.hum1 |
grafana13.2 Red Hat:hummingbird:1 | All versions | 0:13.2.3-0.2.hum1 |
How do I fix CVE-2026-109955?
Upgrade to a fixed version.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-109955 being exploited?
There is no known exploitation of CVE-2026-109955 in the wild and no public exploit code.
Sources
Also known as GHSA-3g9q-qwv8-cxpf, RHSA-2026:84423, RHSA-2026:84431.