XSS in Discourse
CVE-2026-33395
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the discourse-graphviz plugin contains a stored cross-site scripting (XSS) vulnerability that allows authenticated users to inject malicious JavaScript code through DOT graph definitions. For instances with CSP disabled only. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, disable the graphviz plugin, upgrade to a patched version, or enable a content security policy.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.4 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (22.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 23rd percentile — 22.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
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)
References
- github.com/discourse/discourse/security/advisories/GHSA-23c7-gq89-xm5v (Mitigation, Vendor Advisory)
- github.com/discourse/discourse/commit/0471e68ed0b594bf386e068f228849244b880ef1 (Patch)
- github.com/discourse/discourse/commit/0c861df8bea03dcc01b60da6cc7038e6c88de4ee (Patch)
- github.com/discourse/discourse/commit/472f9e1f7855307e489e9eaa6825d5335dfc08b5 (Patch)
Frequently asked questions
- What is CVE-2026-33395?
- CVE-2026-33395 is a medium-severity vulnerability in Discourse, classified under Cross-site Scripting. CVSS score: 4.4/10. Published 2026-03-19.
- How severe is CVE-2026-33395?
- Medium severity. CVSS v3 base score is 4.4 out of 10.