Vulnerability · Published Jun 22, 2026 · Assigned by GitHub_M
CVE-2026-54286Hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)
Medium 5.9
In plain English
A medium-severity path traversal in hono from honojs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 38% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, on Windows hosts, an encoded backslash (%5C) in the request path decodes to \, which the Windows path resolver treats as a separator. serve-static then resolves a single URL segment such as admin\secret.txt into a nested file under the root and serves it, letting an attacker read static files meant to be protected behind prefix-mounted middleware. This vulnerability is fixed in 4.12.25.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | hono | 4.12.25 | GHSA-wwfh-h76j-fc44 |
Affected products (as reported)
Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
References
- https://github.com/honojs/hono/security/advisories/GHSA-wwfh-h76j-fc44 x_refsource_CONFIRM