GHSA-5xfx-xj4h-5p7r SiYuan: Stored XSS to RCE via attribute-view cell rendering in genAVValueHTML()

• Go github.com/siyuan-note/siyuan/kernel: < 0.0.0-20260628153353-2d5d72223df4 → fixed in 0.0.0-20260628153353-2d5d72223df4

Summary The attribute-view (database) cell renderer `genAVValueHTML` interpolates cell content raw in four of its branches: `text`, `url`, `phone`, and `mAsset`. A cell value like `` or `">` breaks out of its surrounding tag and runs arbitrary JavaScript in the renderer when the victim opens the block-attribute panel. On Electron desktop the renderer runs with `nodeIntegration:true`, so the XSS chains to host RCE via `require('child_process')`. AV files live under the workspace and ride normal sync, so an attacker with write access to any synced workspace plants the payload once and it fires on every device that opens a panel containing that row. The kernel doesn't escape on the way in either, so the malicious cell persists byte-for-byte. There's no equivalent of the `html.EscapeAttrVal` call that protects block IAL attributes at `kernel/model/blockial.go:261`. Companion advisory: GHSA-mvjr-vv3c-w4qv. Same workspace-sync to renderer-sink to Electron-RCE pattern in the CSS-snippet renderer, different sink file. Worth auditing for the same pattern in other renderers that pull from synced workspace data. Details Affected: • HEAD `96dfe0b` (v3.6.5, 2026-04-21) • Renderer sink: `app/src/protyle/render/av/blockAttr.ts:68`, `genAVValueHTML()`. The text, url, phone, and mAsset branches interpolate cell content raw. • Callsites piping `genAVValueHTML` into `innerHTML`: `select.ts:124,229,346`, `cell.ts:791,913,1198`, `col.ts:455,656,1256`, `filter.ts:199,471,609,702`, `groups.ts:56,289,328,378`, and `blockAttr.ts:212`. • Source: cell values returned by `/api/av/getAttributeView`. Backing store: `data/storage/av/.json`. • Write path: `kernel/model/attribute_view.go`, `updateAttributeViewValue` and `(*Transaction).doUpdateAttrViewCell`. No call to `html.EscapeAttrVal`, `html.EscapeString`, or `util.EscapeHTML` anywhere in the file. • Electron config: `nodeIntegration:true`, `contextIsolation:false`, `webSecurity:false` on every `BrowserWindow` in `app/electron/main.js:307,408-411,1107-1110,1150-1153,1322`. The sink `app/src/protyle/render/av/blockAttr.ts:68`, with the unsafe branches highlighted: ```ts export const genAVValueHTML = (value: IAVCellValue) => { let html = ""; switch (value.type) { case "block": // escaped via escapeAttr — safe html = ``; break; case "text": // value.text.content goes raw into a html = `${value.text?.content || ""}`; break; case "url": // value.url.content goes raw into value="..." and href="..." html = ` `; break; case "phone": // same pattern as url html = ` `; break; case "mAsset": value.mAsset?.forEach(item => { if (item.type === "image") { // item.content raw inside aria-label html += ``; } else { // attributes escaped, but ${item.name || item.content} text-node is raw html += `${item.name || item.content}`; } }); break; // other cases use escapeHtml / escapeAttr correctly } return html; }; ``` `escapeHtml` and `escapeAttr` already exist and are used in the `block`, `select`, and `mSelect` cases. They just aren't applied in the four branches above. Callers assign the result to `innerHTML`. Example, `app/src/protyle/render/av/select.ts:124`: ```ts if (item.classList.contains("custom-attr__avvalue")) { item.innerHTML = genAVValueHTML(cellValue); } ``` The write path A grep for any HTML-escape call in `kernel/model/attribute_view.go` returns nothing: ``` grep -n 'html.Escape\|EscapeHTML\|EscapeString' kernel/model/attribute_view.go (no output) ``` For comparison, the block-IAL write path at `kernel/model/blockial.go:261` applies `html.EscapeAttrVal(value)`. The AV cell write path is missing the equivalent. Storage and sync AV files live at `data/storage/av/.json` and the repository sync picks them up the same way it does the rest of the workspace data. Any sync target propagates the malicious cell to all peers. Suggested fix The renderer-side fix is the more important one. `escapeHtml` and `escapeAttr` already exist in `blockAttr.ts` and already protect the `block`, `select`, and `mSelect` branches. Extend them to the rest of `genAVValueHTML`: ```ts case "text": html = `${escapeHtml(value.text?.content || "")}`; break; case "url": html = ` `; break; case "phone": html = ` `; break; case "mAsset": // escape item.name and item.content in the text-node positions, not just inside attributes ``` The `mAsset` image branch also interpolates `item.content` into the `src` attribute via `getCompressURL`. Worth rejecting `javascript:` and `data:` schemes for asset URLs while you're in there. Backend side, defense in depth: in `kernel/model/attribute_view.go:updateAttributeViewValue`, call `html.EscapeAttrVal(content)` on the string-content cell types before persisting. This mirrors the existing protection in `kernel/model/blockial.go:261`. The renderer fix matters more because the backend fix doesn't retroactively neutralize payloads already sitting in synced workspaces. PoC Stand up SiYuan and drop a malicious AV file at `workspace/data/storage/av/poc.json`: ```bash docker run -d --name siyuan-poc \ -v ./workspace:/siyuan/workspace \ -p 16806:6806 \ b3log/siyuan:latest \ --workspace=/siyuan/workspace --accessAuthCode=hunter2 ``` Minimum viable AV JSON: ```json { "spec": 2, "id": "20260519999999-poctest", "name": "PocAV", "keyValues": [ { "key": {"id": "...keyblok", "name": "Block", "type": "block"}, "values": [{ "id": "...row1blk", "keyID": "...keyblok", "blockID": "...row1blk", "type": "block", "isDetached": true, "block": {"id": "...row1blk", "content": "Row 1"} }] }, { "key": {"id": "...keytext", "name": "TextField", "type": "text"}, "values": [{ "id": "...celltxt", "keyID": "...keytext", "blockID": "...row1blk", "type": "text", "text": {"content": ""} }] }, { "key": {"id": "...keyurl0", "name": "UrlField", "type": "url"}, "values": [{ "id": "...cellurl", "keyID": "...keyurl0", "blockID": "...row1blk", "type": "url", "url": {"content": "\">"} }] } ] } ``` In a real attack the file gets there via sync, not by hand. Confirm the API returns the cell content raw: ```bash TOKEN=$(jq -r '.api.token' workspace/conf/conf.json) curl -s -X POST http://localhost:16806/api/av/getAttributeView \ -H "Authorization: Token $TOKEN" \ -d '{"id":"20260519999999-poctest"}' \ | python3 -m json.tool | grep -E '"content":' ``` Output from my run on 2026-05-19: ``` "content": "" "content": "\">" ``` `` and `">` come back …