CVE-2023-26040: Discourse chat messages susceptible to Cross-site Scripting through chat excerpts

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-03-17 · updated 2026-06-17
Weakness: CWE-79

Description

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.

Affected products

discourse: 3.1.0-beta2

References

https://github.com/discourse/discourse/commit/a373bf2a01488c206e7feb28a9d2361b22ce6e70
https://github.com/discourse/discourse/security/advisories/GHSA-ccfc-qpmp-gq87
https://github.com/discourse/discourse/commit/a373bf2a01488c206e7feb28a9d2361b22ce6e70
https://github.com/discourse/discourse/security/advisories/GHSA-ccfc-qpmp-gq87

Get alerted when CVE-2023-26040 or the next vulnerability affects your stack