CVE-2026-29087 @hono/node-server: Authorization bypass for protected static paths via encoded slashes in Serve Static Middleware
Attackers can bypass authorization checks on protected static files by using encoded slashes, allowing unauthorized access to sensitive resources.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-29087?
CVE-2026-29087 is a high-severity authentication bypass vulnerability in honojs node-server, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
@hono/node-server allows running the Hono application on Node.js. Prior to version 1.19.10, when using @hono/node-server's static file serving together with route-based middleware protections (e.g. protecting /admin/*), inconsistent URL decoding can allow protected static resources to be accessed without authorization. In particular, paths containing encoded slashes (%2F) may be evaluated differently by routing/middleware matching versus static file path resolution, enabling a bypass where middleware does not run but the static file is still served. This issue has been patched in version 1.19.10.
Weakness: CWE-863
Which versions are affected by CVE-2026-29087?
2 open source packages ship an affected version, including @hono/node-server. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
@hono/node-server npm | All versions | 1.19.10 |
@hono/node-server npm | All versions | 1.19.10 |
Products include Hono Node-Server.
How do I fix CVE-2026-29087?
Upgrade @hono/node-server to 1.19.10 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-29087 being exploited?
There is no known exploitation of CVE-2026-29087 in the wild and no public exploit code.
Other vulnerabilities in honojs node-server
Sources
Also known as CLEANSTART-2026-DD25783, CLEANSTART-2026-JJ09518, CLSA-2026-1793207049, GHSA-wc8c-qw6v-h7f6, MINI-5wh8-w6hm-pgxm, MINI-gg79-r5mh-4jxx and 5 more.