Félix Malfait
8da69e0f77
## Summary
- Fixes **GHSA-7w89-7q26-gj7q**: stored XSS via `javascript:` URIs in
BlockNote `FileBlock` `props.url`, rendered as a clickable `<a href>`.
- Audited the full codebase and hardened **all** surfaces where
user-controlled URLs are rendered as `href` or passed to `window.open`.
- Applies defense-in-depth: server-side input validation + client-side
render-time checks + lint rules to prevent regressions.
### Changes
**New utility** — `isSafeUrl` (`~/utils/isSafeUrl.ts`):
Allowlists `http:`, `https:`, `mailto:`, `tel:` protocols and relative
paths (`/`). Returns `false` for `javascript:`, `data:`, `vbscript:`,
etc.
**Server-side** — `validateBlocknoteFieldOrThrow`:
- Recursively walks all blocks and validates `props.url` and inline link
`href` values
- Rejects payloads with unsafe URL protocols at save time (before data
is stored)
**Client-side** — 8 components hardened:
| Component | Fix |
|-----------|-----|
| `FileBlock` (reported vuln) | `isSafeUrl` gate, fixed
`target="__blank"` → `_blank`, added `rel="noopener noreferrer"` |
| `LazyMarkdownRenderer` | `isSafeUrl` gate on markdown `<a href>`,
added `target`/`rel` |
| `EditLinkPopover` (TipTap) | Validates + auto-prefixes `https://`,
rejects unsafe URLs |
| `LinkBubbleMenu` (TipTap) | `isSafeUrl` gate on `window.open`, added
`noopener,noreferrer` |
| `AttachmentRow` | `isSafeUrl` gate on file attachment `href` |
| `URLDisplay` / `LinkDisplay` | `isSafeUrl` as second check after
`startsWith('http')` |
| `IframeWidget` | `isSafeUrl` gate on `src`, shows error state for
unsafe URLs |
| `InformationBannerMaintenance` | `isSafeUrl` gate on `window.open` |
**Lint rules** — `.oxlintrc.json`:
- `no-script-url: error` — catches `javascript:` string literals
- `react/jsx-no-script-url: error` — catches `javascript:` in JSX href
attributes
## Test plan
- [ ] Create a note via GraphQL mutation with `"url":
"javascript:void(alert(1))"` in a file block — should be rejected by
server validation
- [ ] Verify existing file attachments in notes still render and are
clickable
- [ ] Verify TipTap link insertion works for normal `https://` URLs
- [ ] Verify TipTap link insertion rejects `javascript:` URIs
- [ ] Verify markdown links in AI chat render correctly for safe URLs
- [ ] Verify URL/Link field displays still work for normal URLs
- [ ] Verify iframe widget rejects non-http(s) URLs
Made with [Cursor](https://cursor.com)
---------
Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
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