SiYuan: Electron Renderer RCE via decodeURIComponent-driven tooltip XSS in aria-label sink (incomplete fix for CVE-2026-34585)
Date: 2026-05
Affected: go/github.com/siyuan-note/siyuan/kernel
Attack vector: xss
Category: vulnerability-disclosure
Severity: Critical
CVE: CVE-2026-44588
CWE: CWE-116
CWE-1188
CWE-79

## Summary The tooltip mouseover handler in `app/src/block/popover.ts` reads `aria-label` via `getAttribute` and passes it through `decodeURIComponent` before assigning to `messageElement.innerHTML` in `app/src/dialog/tooltip.ts:41`. The encoder used at the producer side, `escapeAriaLabel` in `app/src/util/escape.ts:19-25`, only handles HTML special characters (`"`, `'`, `<`, literal `&lt;`) — it leaves `%XX` URL-escapes untouched. So a doc title containing `%3Cimg src=x onerror=...%3E` round-trips through `escapeAriaLabel` and the HTML attribute layer unmodified. Then `decodeURIComponent` on the consumer side converts `%3C` to a literal `<` character (a real `<`, NOT a character reference). When that string is assigned to `innerHTML`, the HTML5 tokenizer enters TagOpenState on the literal `<`, parses the `<img>` element, and the `onerror` handler fires. Because the renderer runs with `nodeIntegration: true, contextIsolation: false, webSecurity: false` (`app/electron/main.js:407-411`), `require('child_process')` is reachable from the injected handler, escalating to arbitrary code execution. Doc titles, AV column names + descriptions, AV select options, file-tree tooltips all reach this sink because they're rendered into `class="ariaLabel"` elements with `aria-label="${escapeAriaLabel(...)}"`. Doc title is the easiest plant — any user with create/rename access lands the payload, and the file survives `.sy.zip` round-trip without modification. ## Why a "double HTML-decode"


Mitigations:

Architectural layers (MAESTRO):