Path Traversal in Honojs Hono
CVE-2026-54286
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.
Vulnerability class: Path Traversal (Directory Traversal)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.004 (35.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 35.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Honojs Hono — versions < 4.12.25
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-54286?
- CVE-2026-54286 is a medium-severity vulnerability in Honojs Hono, classified under Path Traversal. CVSS score: 5.9/10. Published 2026-06-22.
- How severe is CVE-2026-54286?
- Medium severity. CVSS v3 base score is 5.9 out of 10.