{"id":"GHSA-wwfh-h76j-fc44","summary":"hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)","details":"### Summary\n\nOn 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. Directory escape (`..`) remains blocked.\n\n### Details\n\nThe router splits paths only on `/`, so `/admin%5Csecret.txt` is one segment and middleware on `/admin/*` does not run. The `serve-static` guard rejects `.`/`..` and consecutive separators but lets a lone `\\` through; on Windows the file resolver re-splits it into the protected subtree.\n\nThis affects Windows hosts serving static files via the Node, Bun, or Deno adapters that guard a static subtree with prefix-mounted middleware.\n\n### Impact\n\nAn unauthenticated attacker can read static files under a middleware-guarded prefix on Windows hosts. The read stays within the configured root; escape outside the root is not possible.","aliases":["CVE-2026-54286"],"modified":"2026-07-21T17:01:15.047285639Z","published":"2026-06-16T14:09:03Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-06-16T14:09:03Z","nvd_published_at":"2026-06-22T18:16:47Z","cwe_ids":["CWE-22"],"severity":"MODERATE"},"references":[{"type":"WEB","url":"https://github.com/honojs/hono/security/advisories/GHSA-wwfh-h76j-fc44"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54286"},{"type":"PACKAGE","url":"https://github.com/honojs/hono"}],"affected":[{"package":{"name":"hono","ecosystem":"npm","purl":"pkg:npm/hono"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.12.25"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-wwfh-h76j-fc44/GHSA-wwfh-h76j-fc44.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"}]}