{"id":"CVE-2026-54286","aliases":["CLSA-2026-1790597695","EUVD-2026-38327","GHSA-26pp-8wgv-hjvm","GHSA-wwfh-h76j-fc44","ROOT-APP-NPM-CVE-2026-54286"],"status":"published","title":"Hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)","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.","severity":{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00433,"percentile":0.37903,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-22"],"published":"2026-06-16T14:09:03Z","modified":"2026-10-28T02:30:50Z","fixes":[{"ecosystem":"npm","package":"hono","fixed_in":["4.12.25"],"sources":["ghsa","osv"]},{"ecosystem":"Root:npm","package":"hono","fixed_in":["4.12.14-aikido.7","4.12.14-aikido.8","4.12.12-aikido.2","4.12.25-aikido.1"],"sources":["osv"]},{"ecosystem":"Root:npm","package":"@rootio/hono","fixed_in":["4.12.14-root.io.7","4.12.14-root.io.8","4.12.12-root.io.2","4.12.25-root.io.1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"hono","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.12.25"}]}]},{"source":"osv","ecosystem":"TuxCare:npm","package":"hono","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.12.12-tuxcare.0"},{"fixed":"3.12.12-tuxcare.2"}]}],"versions":["3.12.12","3.12.12-tuxcare.1"],"bundled":11},{"source":"osv","ecosystem":"npm","package":"hono","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.12.25"}]}]},{"source":"osv","ecosystem":"Root:npm","package":"hono","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.12.14-aikido.7"},{"fixed":"4.12.14-aikido.8"},{"fixed":"4.12.12-aikido.2"},{"fixed":"4.12.25-aikido.1"}]}]},{"source":"osv","ecosystem":"Root:npm","package":"@rootio/hono","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.12.14-root.io.7"},{"fixed":"4.12.14-root.io.8"},{"fixed":"4.12.12-root.io.2"},{"fixed":"4.12.25-root.io.1"}]}]}],"products":[{"vendor":"honojs","product":"hono"}],"references":[{"url":"https://github.com/honojs/hono/security/advisories/GHSA-wwfh-h76j-fc44","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54286","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-wwfh-h76j-fc44"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54286.json","tags":["advisory"]},{"url":"https://github.com/honojs/hono","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-54286","title":"Hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)","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.","status":"published","published":"2026-06-22T17:14:40.133Z","modified":"2026-06-23T14:07:34.188Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T13:37:58.613221Z"}],"euvd":[{"id":"EUVD-2026-38327","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.","status":"published","published":"2026-06-22T17:14:40Z","modified":"2026-06-23T14:07:34Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T18:20:33.324654Z"}],"ghsa":[{"id":"GHSA-wwfh-h76j-fc44","title":"hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)","description":"### 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.","status":"published","published":"2026-06-16T14:09:03Z","modified":"2026-07-21T15:27:08Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T14:40:49.410128Z"}],"nvd":[{"id":"CVE-2026-54286","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.","status":"published","published":"2026-06-22T18:16:47.213Z","modified":"2026-10-25T23:10:00.167Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T14:12:24.912854Z"}],"osv":[{"id":"CVE-2026-54286","title":"Hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)","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.","status":"published","published":"2026-06-22T17:14:40.133Z","modified":"2026-10-28T02:30:50.408079896Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T15:45:10.818486Z"},{"id":"GHSA-wwfh-h76j-fc44","title":"hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)","description":"### 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.","status":"published","published":"2026-06-16T14:09:03Z","modified":"2026-09-10T03:50:51.049920484Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T15:46:59.131095Z"},{"id":"CLSA-2026-1790597695","title":"TuxCare security update for hono (12 CVEs)","description":"TuxCare rebuilt hono to address 12 CVEs. Fixed in 3.12.12-tuxcare.2.","status":"published","published":"2026-09-28T12:14:55Z","modified":"2026-10-15T09:48:03.104113003Z","updated_at":"2026-11-02T15:43:48.65893Z"},{"id":"ROOT-APP-NPM-CVE-2026-54286","title":"CVE-2026-54286 in hono - Patched by Root","description":"Root has patched CVE-2026-54286 in the hono package for Root:npm. Multiple fixed versions available.","status":"published","published":"2026-09-25T06:19:53Z","modified":"2026-09-25T07:15:21.826982085Z","updated_at":"2026-11-02T15:53:27.649662Z"}]}}