CVE-2023-26040 — Discourse is an open-source discussion platform

Discourse is an open-source discussion platform. Between versions 3.1.0.beta2 and 3.1.0.beta3 of the `tests-passed` branch, editing or responding to a chat message containing malicious content could lead to a cross-site scripting attack. This issue is patched in version 3.1.0.bet

01What is this vulnerability?

Discourse is an open-source discussion platform. Between versions 3.1.0.beta2 and 3.1.0.beta3 of the `tests-passed` branch, editing or responding to a chat message containing malicious content could lead to a cross-site scripting attack. This issue is patched in version 3.1.0.beta3 of the `tests-passed` branch. There are no known workarounds.

02Affected products

Vendor	Product	Versions
discourse	discourse	tests-passed > 3.1.0.beta2, < 3.1.0.beta3

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2023-03-17T14:45:35.889Z
• Last modified: 2025-02-25T14:54:32.522Z

09References

• github.com — https://github.com/discourse/discourse/security/advisories/GHSA-ccfc-qpmp-gq87
• github.com — https://github.com/discourse/discourse/commit/a373bf2a01488c206e7feb28a9d2361b22…