What’s Vulnerable › Vulnerabilities
CVE-2026-33425: Discourse has inferable private group membership or existence via exclude_groups parameter
- Severity: medium (CVSS 5.3 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.7% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2026-03-21 · updated 2026-06-17
- Weakness: CWE-203
Description
Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, unauthenticated users can determine whether a specific user is a member of a private group by observing changes in directory results when using the `exclude_groups` parameter. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, disable public access to the user directory via Admin → Settings → hide user profiles from public.
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
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