CVE-2026-29045 Hono: Arbitrary file access via serveStatic vulnerability
Attackers can bypass middleware protections to access protected static files in Hono applications using serveStatic due to inconsistent URL decoding.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-29045?
CVE-2026-29045 is a high-severity missing authorization vulnerability in honojs hono, published on 4 Mar 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. Prior to version 4.12.4, when using serveStatic together with route-based middleware protections (e.g. app.use('/admin/*', ...)), inconsistent URL decoding allowed protected static resources to be accessed without authorization. The router used decodeURI, while serveStatic used decodeURIComponent. This mismatch allowed paths containing encoded slashes (%2F) to bypass middleware protections while still resolving to the intended filesystem path. This issue has been patched in version 4.12.4.
Weakness: CWE-177
Which versions are affected by CVE-2026-29045?
2 open source packages ship an affected version, including hono. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
hono npm | All versions | 4.12.4 |
hono npm | All versions | 4.12.4 |
Products include Hono Hono.
How do I fix CVE-2026-29045?
Upgrade hono to 4.12.4 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-29045 being exploited?
There is no known exploitation of CVE-2026-29045 in the wild and no public exploit code.
Other vulnerabilities in honojs hono
- CVE-2026-27700 Hono is Vulnerable to Authentication Bypass by IP Spoofing in AWS Lambda ALB conninfo
- CVE-2026-22817 JWT Algorithm Confusion via Unsafe Default (HS256) in Hono JWT Middleware Allows Token Forgery and Auth Bypass
- CVE-2026-22818 JWT algorithm confusion in Hono JWK Auth Middleware when JWK lacks "alg" (untrusted header.alg fallback)
- CVE-2025-62610 Hono Improperly Authorizes JWT Audience Validation
- CVE-2025-58362 Hono contains a flaw in URL path parsing, potentially leading to path confusion
Sources
Also known as CLEANSTART-2026-BV20490, CLEANSTART-2026-FT93367, GHSA-q5qw-h33p-qvwr, MINI-8c2j-564f-3qgx, MINI-9xrh-59cp-xr9v, MINI-c55f-r88f-28rp and 3 more.