GHSA-P4M3-MGMM-C664

Vulnerability from github – Published: 2026-07-10 19:25 – Updated: 2026-07-10 19:25
VLAI
Summary
SiYuan: Path Traversal via Double URL Encoding in /assets/*path (publish mode arbitrary file─read), Incomplete fix of CVE-2026-41894
Details

Summary

The patch for CVE-2026-41894 ("Path Traversal via Double URL Encoding") sanitized the /export/ route but the identical root cause remains in the /assets/*path route. In publish mode (anonymous read-only HTTP endpoint, default port 6808), an unauthenticated remote attacker can read arbitrary files inside WorkspaceDir — including conf/conf.json (which contains the AccessAuthCode SHA256 hash, API token, and sync keys), temp/siyuan.db, temp/blocktree.db, and siyuan.log — by double-URL-encoding .. segments.

Verified against siyuan v3.6.5: - GET /assets/%252e%252e/%252e%252e/conf/conf.jsonHTTP 200, 10349 bytes (conf.json served) - GET /export/%252e%252e/%252e%252e/conf/conf.json → HTTP 401 (patched) - GET /assets/%2e%2e/conf/conf.json → HTTP 404 (single-decode handled correctly)

## Vulnerable Code

Step 1 — route & first decode (kernel/server/serve.go:587-626): The router registers GET /assets/*path for the publish listener. Gin performs one URL decoding pass on URL.Path, so a request for /assets/%252e%252e/... yields context.Param("path") == "/%2e%2e/%2e%2e/conf/conf.json" — literal %2e%2e strings, which path.Clean cannot collapse.

Step 2 — second decode via fallback (kernel/model/assets.go:536-563, GetAssetAbsPath): go p, err := getAssetAbsPath(relativePath) if nil != err { // fallback decoded, e := url.PathUnescape(relativePath) // ← line 548, second decode if nil == e { p, err = getAssetAbsPath(decoded) } } After the fallback decodes %2e%2e to .., filepath.Join(DataDir, "../../conf/conf.json") is Clean-ed to WorkspaceDir/conf/conf.json, an existing file.

Step 3 — publish-mode access gate fall-through (kernel/model/publish_access.go:288, CheckAbsPathAccessableByPublishAccess): go if !filelock.IsSubPath(util.DataDir, absPath) { return true // ← fall-through allows anything outside DataDir but inside WorkspaceDir } Because the resolved file is outside DataDir (it's in WorkspaceDir), the gate returns true and IsSensitivePath() is never invoked — .db / .log / conf/ denylists do not apply to the /assets/ route at all (unlike the patched /export/ route, which additionally checks IsSubPath(exportBaseDir, ...)).

Step 4 — file served (http.ServeFile): the request URL.Path contains literal %2e%2e, not .., so Go's containsDotDot guard passes and the file is sent.

## PoC

Preconditions: siyuan kernel running with publish mode enabled (conf.publish.enable = true). Publish mode is the documented anonymous read-only endpoint for sharing notebooks.

$ curl -i "http://victim:6808/assets/%252e%252e/%252e%252e/conf/conf.json" HTTP/1.1 200 OK Content-Length: 10349 Content-Type: application/json ... {"appearance":{...},"editor":{...},"system":{...},"accessAuthCode":"<sha256>","api":{"token":"<api token>"}, ...}

Compared with the patched route: $ curl -i "http://victim:6808/export/%252e%252e/%252e%252e/conf/conf.json" HTTP/1.1 401 Unauthorized

## Root Cause Three independent flaws combine: 1. GetAssetAbsPath performs a second url.PathUnescape as a "compatibility" fallback, re-introducing the double-decode primitive that the CVE-2026-41894 patch eliminated on /export/. 2. CheckAbsPathAccessableByPublishAccess returns true for any path outside DataDir, even when that path is still inside WorkspaceDir (which contains conf/conf.json, temp/*.db, siyuan.log). 3. The IsSensitivePath() denylist applied to /export/ is not called from the /assets/ handler.

## Impact Unauthenticated remote arbitrary file read inside WorkspaceDir. Confirmed-readable files include: - conf/conf.jsonaccessAuthCode SHA256 (offline crackable), API token, S3/WebDAV sync credentials. - temp/siyuan.db, temp/blocktree.db, temp/asset_content.db — full notebook content (SQLite). - siyuan.log — internal paths, OS username, plugin info.

Compromise of accessAuthCode / API token escalates to authenticated kernel API access (full read/write of all notebooks). Compromise of sync credentials escalates beyond the host.

## Fix 1. Remove the url.PathUnescape fallback in GetAssetAbsPath (assets.go:548), matching the /export/ patch. 2. In CheckAbsPathAccessableByPublishAccess, replace the IsSubPath(DataDir, ...) fall-through with an explicit allowlist (only DataDir and its publishable subtree) and always call IsSensitivePath(). 3. Apply IsSensitivePath() inside the /assets/*path handler in serve.go as defense-in-depth.

## Status Privately reported via GitHub Security Advisory. PoC reproduced locally against v3.6.5 (publish port 6808): GET /assets/%252e%252e/%252e%252e/conf/conf.json returned HTTP 200 / 10349 bytes.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/siyuan-note/siyuan/kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.0-20260628153353-2d5d72223df4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54066"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1188",
      "CWE-22",
      "CWE-23"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-10T19:25:04Z",
    "nvd_published_at": "2026-06-24T22:16:48Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n  The patch for CVE-2026-41894 (\"Path Traversal via Double URL Encoding\") sanitized the `/export/` route but the\n  **identical root cause remains in the `/assets/*path` route**. In publish mode (anonymous read-only HTTP endpoint,\n  default port 6808), an unauthenticated remote attacker can read arbitrary files inside `WorkspaceDir` \u2014 including\n  `conf/conf.json` (which contains the `AccessAuthCode` SHA256 hash, API token, and sync keys), `temp/siyuan.db`,\n  `temp/blocktree.db`, and `siyuan.log` \u2014 by double-URL-encoding `..` segments.\n\n  Verified against siyuan v3.6.5:\n  - `GET /assets/%252e%252e/%252e%252e/conf/conf.json` \u2192 **HTTP 200, 10349 bytes (conf.json served)**\n  - `GET /export/%252e%252e/%252e%252e/conf/conf.json` \u2192 HTTP 401 (patched)\n  - `GET /assets/%2e%2e/conf/conf.json` \u2192 HTTP 404 (single-decode handled correctly)\n\n  ## Vulnerable Code\n\n  **Step 1 \u2014 route \u0026 first decode** (`kernel/server/serve.go:587-626`):\n  The router registers `GET /assets/*path` for the publish listener. Gin performs one URL decoding pass on `URL.Path`,\n  so a request for `/assets/%252e%252e/...` yields `context.Param(\"path\") == \"/%2e%2e/%2e%2e/conf/conf.json\"` \u2014 literal\n  `%2e%2e` strings, which `path.Clean` cannot collapse.\n\n  **Step 2 \u2014 second decode via fallback** (`kernel/model/assets.go:536-563`, `GetAssetAbsPath`):\n  ```go\n  p, err := getAssetAbsPath(relativePath)\n  if nil != err {\n      // fallback\n      decoded, e := url.PathUnescape(relativePath)   // \u2190 line 548, second decode\n      if nil == e {\n          p, err = getAssetAbsPath(decoded)\n      }\n  }\n  ```\n  After the fallback decodes `%2e%2e` to `..`, `filepath.Join(DataDir, \"../../conf/conf.json\")` is `Clean`-ed to\n  `WorkspaceDir/conf/conf.json`, an existing file.\n\n  **Step 3 \u2014 publish-mode access gate fall-through** (`kernel/model/publish_access.go:288`,\n  `CheckAbsPathAccessableByPublishAccess`):\n  ```go\n  if !filelock.IsSubPath(util.DataDir, absPath) {\n      return true   // \u2190 fall-through allows anything outside DataDir but inside WorkspaceDir\n  }\n  ```\n  Because the resolved file is *outside* `DataDir` (it\u0027s in `WorkspaceDir`), the gate returns `true` and\n  `IsSensitivePath()` is never invoked \u2014 `.db` / `.log` / `conf/` denylists do not apply to the `/assets/` route at all\n  (unlike the patched `/export/` route, which additionally checks `IsSubPath(exportBaseDir, ...)`).\n\n  **Step 4 \u2014 file served** (`http.ServeFile`): the request `URL.Path` contains literal `%2e%2e`, not `..`, so Go\u0027s\n  `containsDotDot` guard passes and the file is sent.\n\n  ## PoC\n\n  Preconditions: siyuan kernel running with publish mode enabled (`conf.publish.enable = true`). Publish mode is the\n  documented anonymous read-only endpoint for sharing notebooks.\n\n  ```\n  $ curl -i \"http://victim:6808/assets/%252e%252e/%252e%252e/conf/conf.json\"\n  HTTP/1.1 200 OK\n  Content-Length: 10349\n  Content-Type: application/json\n  ...\n  {\"appearance\":{...},\"editor\":{...},\"system\":{...},\"accessAuthCode\":\"\u003csha256\u003e\",\"api\":{\"token\":\"\u003capi token\u003e\"}, ...}\n  ```\n\n  Compared with the patched route:\n  ```\n  $ curl -i \"http://victim:6808/export/%252e%252e/%252e%252e/conf/conf.json\"\n  HTTP/1.1 401 Unauthorized\n  ```\n\n  ## Root Cause\n  Three independent flaws combine:\n  1. `GetAssetAbsPath` performs a second `url.PathUnescape` as a \"compatibility\" fallback, re-introducing the\n  double-decode primitive that the CVE-2026-41894 patch eliminated on `/export/`.\n  2. `CheckAbsPathAccessableByPublishAccess` returns `true` for any path outside `DataDir`, even when that path is still\n   inside `WorkspaceDir` (which contains `conf/conf.json`, `temp/*.db`, `siyuan.log`).\n  3. The `IsSensitivePath()` denylist applied to `/export/` is not called from the `/assets/` handler.\n\n  ## Impact\n  Unauthenticated remote arbitrary file read inside `WorkspaceDir`. Confirmed-readable files include:\n  - `conf/conf.json` \u2014 `accessAuthCode` SHA256 (offline crackable), API token, S3/WebDAV sync credentials.\n  - `temp/siyuan.db`, `temp/blocktree.db`, `temp/asset_content.db` \u2014 full notebook content (SQLite).\n  - `siyuan.log` \u2014 internal paths, OS username, plugin info.\n\n  Compromise of `accessAuthCode` / API token escalates to authenticated kernel API access (full read/write of all\n  notebooks). Compromise of sync credentials escalates beyond the host.\n\n  ## Fix\n  1. Remove the `url.PathUnescape` fallback in `GetAssetAbsPath` (assets.go:548), matching the `/export/` patch.\n  2. In `CheckAbsPathAccessableByPublishAccess`, replace the `IsSubPath(DataDir, ...)` fall-through with an explicit\n  allowlist (only `DataDir` and its publishable subtree) and **always** call `IsSensitivePath()`.\n  3. Apply `IsSensitivePath()` inside the `/assets/*path` handler in `serve.go` as defense-in-depth.\n\n  ## Status\n  Privately reported via GitHub Security Advisory. PoC reproduced locally against v3.6.5 (publish port 6808): `GET\n  /assets/%252e%252e/%252e%252e/conf/conf.json` returned HTTP 200 / 10349 bytes.",
  "id": "GHSA-p4m3-mgmm-c664",
  "modified": "2026-07-10T19:25:04Z",
  "published": "2026-07-10T19:25:04Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-p4m3-mgmm-c664"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54066"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/siyuan-note/siyuan"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "SiYuan: Path Traversal via Double URL Encoding in /assets/*path (publish mode arbitrary   file\u2500read), Incomplete fix of CVE-2026-41894 "
}



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