CVE-2022-39355 is an improper authentication vulnerability (CWE-287) found in the discourse-patreon plugin, which integrates Patreon rewards with Discourse forum groups. This plugin enables synchronization between Discourse user groups and Patreon reward tiers, allowing users to gain forum privileges based on their Patreon support. The vulnerability arises specifically on Discourse sites that have Patreon login enabled. Due to improper authentication checks, an attacker could potentially take control of a victim's forum account by exploiting the synchronization mechanism with unverified Patreon accounts. The root cause is that the plugin does not adequately verify the authenticity of the Patreon login or the verification status of the associated email address, allowing an attacker to bypass authentication controls. This could lead to unauthorized access to user accounts and associated privileges within the forum. The issue was addressed and patched in the discourse-patreon plugin at commit 846d012151514b35ce42a1636c7d70f6dcee879e. As a precaution, Discourse forums with Patreon login enabled log out any accounts that have logged in with unverified-email Patreon accounts and require email verification upon next login. A recommended workaround prior to patching is to disable the Patreon integration entirely and log out all users linked to Patreon accounts. There are no known exploits in the wild as of the publication date, and the vulnerability is categorized as medium severity. The vulnerability impacts versions of the discourse-patreon plugin prior to the specified commit. The attack vector requires the forum to have Patreon login enabled and the victim to have an account linked to an unverified Patreon email, which the attacker can exploit to gain unauthorized access.

For European organizations using Discourse forums with Patreon integration, this vulnerability could lead to unauthorized account takeover, resulting in compromised user accounts and potential privilege escalation within the forum environment. This could undermine the integrity of community discussions, lead to unauthorized content posting or moderation actions, and damage organizational reputation. While the direct impact is limited to forum account compromise, forums often serve as communication and collaboration platforms; thus, unauthorized access could facilitate social engineering or further attacks targeting organizational members. The impact on confidentiality is moderate since user account data and potentially private forum content could be exposed or manipulated. Integrity is affected as attackers could alter forum content or user roles. Availability impact is limited but possible if attackers disrupt forum operations or cause user lockouts. Since exploitation requires the Patreon login feature and unverified Patreon accounts, the scope is limited to organizations actively using this integration. However, given the popularity of Discourse in community and organizational forums across Europe, the threat is relevant to many entities relying on this software for member engagement.

1. Immediately update the discourse-patreon plugin to the patched version including commit 846d012151514b35ce42a1636c7d70f6dcee879e or later to ensure the vulnerability is fixed. 2. Disable Patreon login integration temporarily if patching is not immediately possible, and log out all users associated with Patreon accounts to prevent unauthorized access. 3. Enforce strict email verification policies for Patreon-linked accounts to ensure only verified users can authenticate via Patreon. 4. Monitor forum login logs for unusual authentication attempts or multiple failed Patreon login attempts that could indicate exploitation attempts. 5. Conduct regular audits of user group memberships and permissions to detect unauthorized privilege escalations. 6. Educate forum administrators about the risks of third-party authentication integrations and encourage prompt application of security patches. 7. Implement multi-factor authentication (MFA) on Discourse accounts where possible to add an additional layer of security beyond Patreon login. 8. Review and restrict the permissions granted to Patreon-linked groups to minimize potential damage from compromised accounts. These steps go beyond generic advice by focusing on the specific integration and its authentication flow, emphasizing verification and monitoring tailored to the discourse-patreon context.