{"id":"CVE-2026-54286","aliases":["GHSA-wwfh-h76j-fc44"],"url":"https://o3.security/vulnerability/CVE-2026-54286","summary":"Hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)","details":"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.","published":"2026-06-22T17:14:40.133Z","modified":"2026-08-12T03:51:11.366887919Z","cvss":{"score":5.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"},"epss":{"score":0.00433,"percentile":0.3617,"asOf":"2026-09-01"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"hono","fixedVersion":"4.12.25"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54286.json"},{"type":"ADVISORY","url":"https://github.com/honojs/hono/security/advisories/GHSA-wwfh-h76j-fc44"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54286"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:11.366887919Z"}}