CVE-2026-33425 PUBLISHED

Discourse has inferable private group membership or existence via exclude_groups parameter

Assigner: GitHub_M
Reserved: 19.03.2026 Published: 20.03.2026 Updated: 20.03.2026

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.

Metrics

CVSS 4.0

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS Score: 6.9

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	Low	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	discourse
Product	discourse
Versions	Version >= 2026.1.0-latest, < 2026.1.2 is affected Version >= 2026.2.0-latest, < 2026.2.1 is affected Version = 2026.3.0-latest is affected

References

https://github.com/discourse/discourse/security/advisories/GHSA-r6rh-xvf5-r5f2

Problem Types

CWE-203: Observable Discrepancy CWE
CWE-639: Authorization Bypass Through User-Controlled Key CWE
CWE-862: Missing Authorization CWE