GHSA-FRVP-7C67-39W9
Vulnerability from github – Published: 2026-07-21 18:17 – Updated: 2026-08-12 18:26The same as the hono core Path traversal in serve-static on Windows via encoded backslash (%5C).
Summary
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. Directory escape (..) remains blocked.
Details
The 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.
This affects Windows hosts serving static files via the Node, Bun, or Deno adapters that guard a static subtree with prefix-mounted middleware.
Impact
An 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.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "@hono/node-server"
},
"ranges": [
{
"events": [
{
"introduced": "2.0.0"
},
{
"fixed": "2.0.5"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "npm",
"name": "@hono/node-server"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.19.15"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-21T18:17:25Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "The same as the `hono` core [Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)](https://github.com/honojs/hono/security/advisories/GHSA-wwfh-h76j-fc44).\n\n### 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.",
"id": "GHSA-frvp-7c67-39w9",
"modified": "2026-08-12T18:26:49Z",
"published": "2026-07-21T18:17:25Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/honojs/node-server/security/advisories/GHSA-frvp-7c67-39w9"
},
{
"type": "WEB",
"url": "https://github.com/honojs/node-server/commit/cd076e117cfe4cb8d31f9eb11d2e8f38a6cb8faf"
},
{
"type": "PACKAGE",
"url": "https://github.com/honojs/node-server"
},
{
"type": "WEB",
"url": "https://github.com/honojs/node-server/releases/tag/v2.0.5"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Node.js Adapter for Hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)"
}
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