CVE-2026-40318

## Summary The endpoint `/api/av/removeUnusedAttributeView` is vulnerable to a **path traversal (CWE-22)** that allows an attacker to delete arbitrary `.json` files on the server. The issue arises because user-controlled input (`id`) is directly used in filesystem path construction without validation or restriction. > 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. --- ## Steps To Reproduce 1. Ensure the target instance has the publish service enabled (or any valid access to the endpoint). 2. Send the following request: ```http POST /api/av/removeUnusedAttributeView HTTP/1.1 Host: <target> Content-Type: application/json { "id": "../../../conf/conf" } ``` 3. Observe that the request is accepted. 4. The server resolves the path outside the intended directory and deletes the target file. --- ## Impact An attacker can delete arbitrary `.json` files within the workspace directory. This may lead to: * Deletion of global configuration files (e.g., `conf/conf.json`) * Loss of user data and application state * Corruption of workspace metadata * Persistent application instability or forced recovery This represents a **server-side arbitrary file deletion primitive**, which can have severe impact depending on the targeted files. --- ## Technical Details The vulnerable code constructs file paths as follows: ```go filepath.Join(util.DataDir, "storage", "av", id+".json") ``` Because `id` is not validated, attackers can inject path traversal sequences such as `../` to escape the intended directory. ### Example payloads * `../local` → `data/storage/local.json` * `../../storage/outline` → `data/storage/outline.json` * `../../../conf/conf` → `conf/conf.json` No validation or restriction is applied to: * input format * path normalization * directory boundaries --- ## Root Cause * Untrusted user input (`id`) is directly used in filesystem path construction * No input validation or sanitization * No enforcement that the resolved path stays within the intended directory --- ## Remediation 1. **Validate input strictly** * Only allow valid Attribute View IDs * Reject any input containing path traversal sequences 2. **Enforce directory boundaries** ```go base := filepath.Join(util.DataDir, "storage", "av") absPath := filepath.Join(base, id+".json") if !util.IsSubPath(base, absPath) { return error } ``` 3. **Normalize paths before use** * Ensure canonical paths cannot escape the base directory 4. **Add additional logical checks** * Verify that the target object is valid and allowed to be deleted ---

SiYuan: Publish Reader Path Traversal Delete via `removeUnusedAttributeView` in github.com/siyuan-note/siyuan/kernel. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. (If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.) The additional affected modules and versions are: github.com/siyuan-note/siyuan/kernel before 3.6.40.0.0-20260407035653-2f416e5253f1.