XSS in Discourse

CVE-2025-22602

Discourse is an open source platform for community discussion. In affected versions an attacker can execute arbitrary JavaScript on users' browsers by posting a malicious video placeholder html element. 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.

Vulnerability class: XSS (Cross-Site Scripting)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L.

EPSS exploit prediction

EPSS: 0.004 (27.7th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 28th percentile — 27.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-22602: held from 0.004 to 0.004.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

  • Discourse — versions stable: <= 3.3.3, beta: <= 3.4.0.beta3, 3.4.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-22602?
CVE-2025-22602 is a medium-severity vulnerability in Discourse, classified under Cross-site Scripting. CVSS score: 6.5/10. Published 2025-02-04.
How severe is CVE-2025-22602?
Medium severity. CVSS v3 base score is 6.5 out of 10.