{"id":"CVE-2026-47676","aliases":["CLSA-2026-1792232996","EUVD-2026-32924","GHSA-2gcr-mfcq-wcc3","ROOT-APP-NPM-CVE-2026-47676"],"status":"published","title":"Hono: app.mount() strips mount prefix using undecoded path, causing incorrect routing for percent-encoded paths","description":"Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, app.mount() strips the mount prefix from the incoming request path using the raw URL pathname, while route matching is performed against the percent-decoded path. This inconsistency causes the prefix to be stripped at the wrong position when the path contains percent-encoded multi-byte characters, resulting in the mounted sub-application receiving an incorrect path. This vulnerability is fixed in 4.12.21.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.0026,"percentile":0.17762,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-444","CWE-693"],"published":"2026-05-28T15:26:01Z","modified":"2026-10-28T02:31:04Z","fixes":[{"ecosystem":"npm","package":"hono","fixed_in":["4.12.21"],"sources":["ghsa","osv"]},{"ecosystem":"Root:npm","package":"@rootio/hono","fixed_in":["4.12.14-root.io.6","4.12.14-root.io.7","4.12.14-root.io.8","4.12.12-root.io.2"],"sources":["osv"]},{"ecosystem":"Root:npm","package":"hono","fixed_in":["4.12.14-aikido.6","4.12.14-aikido.7","4.12.14-aikido.8","4.12.12-aikido.2"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"hono","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.12.21"}]}]},{"source":"osv","ecosystem":"TuxCare:npm","package":"hono","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.12.12-tuxcare.0"},{"fixed":"3.12.12-tuxcare.4"}]}],"versions":["3.12.12","3.12.12-tuxcare.1","3.12.12-tuxcare.2","3.12.12-tuxcare.3"],"bundled":2},{"source":"osv","ecosystem":"npm","package":"hono","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.12.21"}]}]},{"source":"osv","ecosystem":"Root:npm","package":"@rootio/hono","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.12.14-root.io.6"},{"fixed":"4.12.14-root.io.7"},{"fixed":"4.12.14-root.io.8"},{"fixed":"4.12.12-root.io.2"}]}]},{"source":"osv","ecosystem":"Root:npm","package":"hono","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.12.14-aikido.6"},{"fixed":"4.12.14-aikido.7"},{"fixed":"4.12.14-aikido.8"},{"fixed":"4.12.12-aikido.2"}]}]}],"products":[{"vendor":"hono","product":"hono"},{"vendor":"honojs","product":"hono"}],"references":[{"url":"https://github.com/honojs/hono/security/advisories/GHSA-2gcr-mfcq-wcc3","tags":["x_refsource_CONFIRM","Vendor Advisory","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47676","tags":["advisory"]},{"url":"https://github.com/honojs/hono/commit/6cbb025ff87fca1a3d00d0ccca0eaf3a6385c3f1","tags":["web"]},{"url":"https://github.com/honojs/hono/releases/tag/v4.12.21","tags":["web"]},{"url":"https://github.com/advisories/GHSA-2gcr-mfcq-wcc3"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47676.json","tags":["advisory"]},{"url":"https://github.com/honojs/hono","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-47676","title":"Hono: app.mount() strips mount prefix using undecoded path, causing incorrect routing for percent-encoded paths","description":"Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, app.mount() strips the mount prefix from the incoming request path using the raw URL pathname, while route matching is performed against the percent-decoded path. This inconsistency causes the prefix to be stripped at the wrong position when the path contains percent-encoded multi-byte characters, resulting in the mounted sub-application receiving an incorrect path. This vulnerability is fixed in 4.12.21.","status":"published","published":"2026-05-28T15:26:01.672Z","modified":"2026-05-28T19:13:28.934Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-444","CWE-693"],"updated_at":"2026-11-02T13:36:29.327819Z"}],"euvd":[{"id":"EUVD-2026-32924","description":"Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, app.mount() strips the mount prefix from the incoming request path using the raw URL pathname, while route matching is performed against the percent-decoded path. This inconsistency causes the prefix to be stripped at the wrong position when the path contains percent-encoded multi-byte characters, resulting in the mounted sub-application receiving an incorrect path. This vulnerability is fixed in 4.12.21.","status":"published","published":"2026-05-28T15:26:01Z","modified":"2026-05-28T19:13:28Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T18:21:01.680356Z"}],"ghsa":[{"id":"GHSA-2gcr-mfcq-wcc3","title":"Hono: app.mount() strips mount prefix using undecoded path, causing incorrect routing for percent-encoded paths","description":"### Summary\n\n`app.mount()` strips the mount prefix from the incoming request path using the raw URL pathname, while route matching is performed against the percent-decoded path. This inconsistency causes the prefix to be stripped at the wrong position when the path contains percent-encoded multi-byte characters, resulting in the mounted sub-application receiving an incorrect path.\n\n### Details\n\nWhen `app.mount(prefix, subApp)` is called, Hono calculates the number of characters to strip based on the decoded mount prefix length, but then applies that slice to the raw URL pathname. When the URL contains percent-encoded characters that expand to fewer characters when decoded (such as encoded non-ASCII characters), the two representations have different lengths, so the prefix is stripped at the wrong byte offset.\n\nAs a result, the sub-application receives a path that does not correspond to the intended sub-path — it may receive a partial or garbled path instead of the expected value after the mount prefix is removed.\n\nThis issue arises when an application uses `app.mount()` with paths that contain percent-encoded characters, particularly when the mount prefix itself or the request path contains encoded non-ASCII characters.\n\n### Impact\n\nA mounted sub-application may receive an incorrectly stripped path, causing requests to be routed to unintended handlers within the sub-application.\n\nThis may lead to:\n\n- Middleware or route handlers in the sub-application being bypassed or incorrectly matched due to the malformed path\n- Requests reaching sub-application routes that the developer did not intend to be accessible via the mounted path\n\nThis issue affects applications that use `app.mount()` where the request URL may contain percent-encoded characters in the mount prefix or subsequent path segments.","status":"published","published":"2026-06-04T18:01:00Z","modified":"2026-06-04T18:01:03Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"cwes":["CWE-444","CWE-693"],"updated_at":"2026-11-02T14:40:16.698699Z"}],"nvd":[{"id":"CVE-2026-47676","description":"Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, app.mount() strips the mount prefix from the incoming request path using the raw URL pathname, while route matching is performed against the percent-decoded path. This inconsistency causes the prefix to be stripped at the wrong position when the path contains percent-encoded multi-byte characters, resulting in the mounted sub-application receiving an incorrect path. This vulnerability is fixed in 4.12.21.","status":"published","published":"2026-05-28T17:16:32.697Z","modified":"2026-10-14T20:10:00.19Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-444","CWE-693"],"updated_at":"2026-11-02T14:12:21.244426Z"}],"osv":[{"id":"CVE-2026-47676","title":"Hono: app.mount() strips mount prefix using undecoded path, causing incorrect routing for percent-encoded paths","description":"Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, app.mount() strips the mount prefix from the incoming request path using the raw URL pathname, while route matching is performed against the percent-decoded path. This inconsistency causes the prefix to be stripped at the wrong position when the path contains percent-encoded multi-byte characters, resulting in the mounted sub-application receiving an incorrect path. This vulnerability is fixed in 4.12.21.","status":"published","published":"2026-05-28T15:26:01.672Z","modified":"2026-10-28T02:31:04.979389847Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"cwes":["CWE-444","CWE-693"],"updated_at":"2026-11-02T15:45:06.231145Z"},{"id":"GHSA-2gcr-mfcq-wcc3","title":"Hono: app.mount() strips mount prefix using undecoded path, causing incorrect routing for percent-encoded paths","description":"### Summary\n\n`app.mount()` strips the mount prefix from the incoming request path using the raw URL pathname, while route matching is performed against the percent-decoded path. This inconsistency causes the prefix to be stripped at the wrong position when the path contains percent-encoded multi-byte characters, resulting in the mounted sub-application receiving an incorrect path.\n\n### Details\n\nWhen `app.mount(prefix, subApp)` is called, Hono calculates the number of characters to strip based on the decoded mount prefix length, but then applies that slice to the raw URL pathname. When the URL contains percent-encoded characters that expand to fewer characters when decoded (such as encoded non-ASCII characters), the two representations have different lengths, so the prefix is stripped at the wrong byte offset.\n\nAs a result, the sub-application receives a path that does not correspond to the intended sub-path — it may receive a partial or garbled path instead of the expected value after the mount prefix is removed.\n\nThis issue arises when an application uses `app.mount()` with paths that contain percent-encoded characters, particularly when the mount prefix itself or the request path contains encoded non-ASCII characters.\n\n### Impact\n\nA mounted sub-application may receive an incorrectly stripped path, causing requests to be routed to unintended handlers within the sub-application.\n\nThis may lead to:\n\n- Middleware or route handlers in the sub-application being bypassed or incorrectly matched due to the malformed path\n- Requests reaching sub-application routes that the developer did not intend to be accessible via the mounted path\n\nThis issue affects applications that use `app.mount()` where the request URL may contain percent-encoded characters in the mount prefix or subsequent path segments.","status":"published","published":"2026-06-04T18:01:00Z","modified":"2026-09-10T03:51:07.554753223Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"cwes":["CWE-444","CWE-693"],"updated_at":"2026-11-02T15:46:34.338541Z"},{"id":"CLSA-2026-1792232996","title":"TuxCare security update for hono (2 CVEs)","description":"TuxCare rebuilt hono to address 2 CVEs. Fixed in 3.12.12-tuxcare.4.","status":"published","published":"2026-10-17T10:29:56Z","modified":"2026-10-17T13:09:28.769429375Z","updated_at":"2026-11-02T15:43:52.011757Z"},{"id":"ROOT-APP-NPM-CVE-2026-47676","title":"CVE-2026-47676 in @rootio/hono - Patched by Root","description":"Root has patched CVE-2026-47676 in the @rootio/hono package for Root:npm. Multiple fixed versions available.","status":"published","published":"2026-07-27T08:20:49Z","modified":"2026-07-27T13:15:27.652685904Z","updated_at":"2026-11-02T15:53:27.649662Z"}]}}