AIKIDO-2026-10656

TL;DR

The HTML-string renderer pathways serialize editor JSON and ProseMirror-backed fragments into markup strings for downstream embedding and previews. Serialized plain-text fragments and serialized HTML attributes previously interpolated raw attacker-supplied strings into attribute builders and text concatenations without contextual escaping. Untrusted document JSON describing markup-like payloads could therefore influence emitted angle brackets and quotes to introduce executable markup relative to consumer sanitization assumptions. The patch applies shared escaping helpers so emitted attributes and text-node payloads encode problematic HTML delimiter characters consistently.