CVE-2023-22468: Discourse vulnerable to Cross-site Scripting in local oneboxes

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-01-26 · updated 2026-06-17
Weakness: CWE-79

Description

Discourse is an open source platform for community discussion. Versions prior to 2.8.13 (stable), 3.0.0.beta16 (beta) and 3.0.0beta16 (tests-passed), are vulnerable to cross-site Scripting. A maliciously crafted URL can be included in a post to carry out cross-site scripting attacks on sites with disabled or overly permissive CSP (Content Security Policy). Discourse's default CSP prevents this vulnerability. This vulnerability is patched in versions 2.8.13 (stable), 3.0.0.beta16 (beta) and 3.0.0beta16 (tests-passed). As a workaround, enable and/or restore your site's CSP to the default one provided with Discourse.

Affected products

discourse: before 2.8.13; 2.9.0-beta1, 2.9.0-beta10, 2.9.0-beta11, 2.9.0-beta12, 2.9.0-beta13, 2.9.0-beta14 (+9) — fixed in 2.8.13

How to fix

Upgrade to a fixed version: discourse 2.8.13. Check the vendor advisory for mitigations.

References

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