What is CVE-2026-33411?

CVE-2026-33411 is a medium-severity vulnerability in Discourse, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-03-20.

How severe is CVE-2026-33411?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Discourse

CVE-2026-33411

Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have a potential stored XSS in topic titles for the solved posts stream. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, ensure that the Content Security Policy is enabled, and has not been modified in a way which would make it more vulnerable to XSS attacks.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.002 (11.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N.

Affected products

Discourse — versions = 2026.3.0-latest, >= 2026.2.0-latest, < 2026.2.1, >= 2026.1.0-latest, < 2026.1.2

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

security-advisories@github.com (x_refsource_CONFIRM, Mitigation, Vendor Advisory)

Frequently asked questions

What is CVE-2026-33411?: CVE-2026-33411 is a medium-severity vulnerability in Discourse, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-03-20.
How severe is CVE-2026-33411?: Medium severity. CVSS v3 base score is 5.4 out of 10.