CVE-2026-57531 Details

A DOM-based cross-site scripting vulnerability has been identified in Milkdown versions prior to 7.21.3, specifically within the @milkdown/plugin-emoji package. This vulnerability allows unauthenticated attackers to execute arbitrary JavaScript in the context of the host application's origin. The issue arises when a victim pastes content controlled by the attacker, which is then processed by the emoji plugin without proper sanitization. The vulnerability exploits the fact that the parseDOM.getAttrs handler captures raw innerHTML from pasted span elements designated as emojis, and the toMarkdown runner subsequently injects this unsanitized content directly into a live DOM element's innerHTML. This bypasses the DOMPurify sanitization applied during the toDOM conversion, leading to the execution of malicious payloads with each markdown serialization.

Users can update to Milkdown version 7.21.3 or later, where this vulnerability has been addressed.