CVE-2026-40318: SiYuan Path Traversal Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-vw86-c94w-v3x4",
  "modified" : "2026-04-24T20:36:55Z",
  "published" : "2026-04-10T19:32:12Z",
  "aliases" : [ "CVE-2026-40318" ],
  "summary" : "SiYuan: Publish Reader Path Traversal Delete via `removeUnusedAttributeView`",
  "details" : "## Summary\n\nThe endpoint `/api/av/removeUnusedAttributeView` is vulnerable to a **path traversal (CWE-22)** that allows an attacker to delete arbitrary `.json` files on the server.\n\nThe issue arises because user-controlled input (`id`) is directly used in filesystem path construction without validation or restriction.\n\n> Access to this endpoint (e.g., via a Reader-role or publish context) is considered a precondition and not part of the vulnerability. The root cause is unsafe path handling.\n\n---\n\n## Steps To Reproduce\n\n1. Ensure the target instance has the publish service enabled (or any valid access to the endpoint).\n2. Send the following request:\n\n```http\nPOST /api/av/removeUnusedAttributeView HTTP/1.1\nHost: <target>\nContent-Type: application/json\n\n{\n  \"id\": \"../../../conf/conf\"\n}\n```\n\n3. Observe that the request is accepted.\n4. The server resolves the path outside the intended directory and deletes the target file.\n\n---\n\n## Impact\n\nAn attacker can delete arbitrary `.json` files within the workspace directory.\n\nThis may lead to:\n\n* Deletion of global configuration files (e.g., `conf/conf.json`)\n* Loss of user data and application state\n* Corruption of workspace metadata\n* Persistent application instability or forced recovery\n\nThis represents a **server-side arbitrary file deletion primitive**, which can have severe impact depending on the targeted files.\n\n---\n\n## Technical Details\n\nThe vulnerable code constructs file paths as follows:\n\n```go\nfilepath.Join(util.DataDir, \"storage\", \"av\", id+\".json\")\n```\n\nBecause `id` is not validated, attackers can inject path traversal sequences such as `../` to escape the intended directory.\n\n### Example payloads\n\n* `../local` → `data/storage/local.json`\n* `../../storage/outline` → `data/storage/outline.json`\n* `../../../conf/conf` → `conf/conf.json`\n\nNo validation or restriction is applied to:\n\n* input format\n* path normalization\n* directory boundaries\n\n---\n\n## Root Cause\n\n* Untrusted user input (`id`) is directly used in filesystem path construction\n* No input validation or sanitization\n* No enforcement that the resolved path stays within the intended directory\n\n---\n\n## Remediation\n\n1. **Validate input strictly**\n\n   * Only allow valid Attribute View IDs\n   * Reject any input containing path traversal sequences\n\n2. **Enforce directory boundaries**\n\n```go\nbase := filepath.Join(util.DataDir, \"storage\", \"av\")\nabsPath := filepath.Join(base, id+\".json\")\n\nif !util.IsSubPath(base, absPath) {\n    return error\n}\n```\n\n3. **Normalize paths before use**\n\n   * Ensure canonical paths cannot escape the base directory\n\n4. **Add additional logical checks**\n\n   * Verify that the target object is valid and allowed to be deleted\n\n---",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/siyuan-note/siyuan/kernel"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.6.40.0.0-20260407035653-2f416e5253f1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "< 0.0.0-20260407035653-2f416e5253f1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-vw86-c94w-v3x4"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-40318"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/siyuan-note/siyuan"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/siyuan-note/siyuan/releases/tag/v3.6.4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-24" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-10T19:32:12Z",
    "nvd_published_at" : "2026-04-16T23:16:33Z"
  }
}