A board member could store entity-encoded markup in a card title. It stays inert
on the live board (Blaze escapes it; the +viewer sanitizer neutralizes handlers
and keeps the entity payload as text), but the exported index.html embedded a
click handler that read the card title/body via .textContent — which DECODES HTML
entities — and then concatenated those values into content.innerHTML. That SECOND
parse revived the tag (e.g. `<img src=x onerror=...>`) and executed it when a
recipient clicked the card in the export, disclosing all data in that document
(including cards added after the attacker's board membership was removed).
The modal is now built with DOM nodes and the card title/body are assigned through
textContent, never innerHTML, so they are inserted as inert text.
Regression: tests/exportHTMLXss.test.cjs (title/body reach only textContent; no
titleText/allText flows into any innerHTML; a textContent assignment does not
revive an entity-decoded <img>).
(CWE-79 stored XSS, GitHub Security Advisory GHSA-8r5p-4q9j-f5jx.)
Thanks to koyokr and xet7 !
The client HTML export cloned the live DOM and built the whole .zip as an
in-memory blob. Two problems on large boards: infinite scroll keeps only ~10
cards per list in the DOM, so most cards were missing from the export; and the
entire archive was buffered in browser RAM.
Before snapshotting, every list's cardlimit is now lifted so the whole board
renders (then we wait for Blaze to flush). The zip is written with JSZip's
generateInternalStream piped straight to the chosen file via the File System
Access API, chunk by chunk with backpressure, so the archive is never held
whole in memory; browsers without the API fall back to the previous blob
download.
- .close() closes the popup. Until now it was ok, but as the Card
Details are opened in a popup too, .back() must be used to get the
same behaviour back
- .back() is also .close() if there is no "popup layer" left
Lauri Ojansivu
Harry Adel
Lewis Cowles
Martin Filser
Tomasz Borychowski
Giacomo Vespignani
Lewis Cowles