What’s Vulnerable › Vulnerabilities

CVE-2026-33395: Discourse has stored click‑based XSS via Graphviz SVG javascript: links

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-19 · updated 2026-06-17
• Weakness: CWE-79

Description

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.

Affected products

• discourse: from 2026.1.0 before 2026.1.2; from 2026.2.0 before 2026.2.1; 2026.3.0 — fixed in 2026.1.2, 2026.2.1

How to fix

Upgrade to a fixed version: discourse 2026.1.2, 2026.2.1. Check the vendor advisory for mitigations.

References

• https://github.com/discourse/discourse/commit/0471e68ed0b594bf386e068f228849244b880ef1
• https://github.com/discourse/discourse/commit/0c861df8bea03dcc01b60da6cc7038e6c88de4ee
• https://github.com/discourse/discourse/commit/472f9e1f7855307e489e9eaa6825d5335dfc08b5
• https://github.com/discourse/discourse/security/advisories/GHSA-23c7-gq89-xm5v

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