Discourse 2026.2.1 Info Leak: User Directory via exclude_groups
CVE-2026-33425 Published on March 20, 2026
Discourse has inferable private group membership or existence via exclude_groups parameter
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.
Weakness Types
What is a Side Channel Attack Vulnerability?
The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor, which exposes security-relevant information about the state of the product, such as whether a particular operation was successful or not. Discrepancies can take many forms, and variations may be detectable in timing, control flow, communications such as replies or requests, or general behavior. These discrepancies can reveal information about the product's operation or internal state to an unauthorized actor. In some cases, discrepancies can be used by attackers to form a side channel.
CVE-2026-33425 has been classified to as a Side Channel Attack vulnerability or weakness.
What is an Insecure Direct Object Reference / IDOR Vulnerability?
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
CVE-2026-33425 has been classified to as an Insecure Direct Object Reference / IDOR vulnerability or weakness.
What is an AuthZ Vulnerability?
The software does not perform an authorization check when an actor attempts to access a resource or perform an action.
CVE-2026-33425 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2026-33425
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Affected Versions
discourse:- 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.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.