Discord BOLA Vulnerability: Unauthorized Addition to Group DMs via Missing Authorization Check on PUT Endpoint

Vulnerability Overview Vulnerability Name: Any authenticated user can join, read, and post to any group DM by ID (missing authorization check on ) Vulnerability Description: The vulnerability exists in Discord's package, specifically in the file. The endpoint is used to add users to group DMs but lacks permission checks, allowing any authenticated user to add themselves or arbitrary users to group DMs they are not already members of. Once added as a member, users can read the entire private message history and send new messages. This is an authorization issue crossing DM boundaries, resulting in private conversations being visible to unauthorized users. Impact Scope Affected Version: commit Fixed Version: CVSS v3 Base Metrics: - Attack Vector: Network - Attack Complexity: Low - Privileges Required: Low - User Interaction: None - Scope: Unchanged - Confidentiality: High - Integrity: High - Availability: None Remediation Fix Code: In , add authorization checks to the endpoint to ensure only the owner or existing members of a group DM can add new members. Specific Fix: Add authorization check logic to the endpoint, similar to the checks present in the endpoint. POC Code Impact Confidentiality: Any authenticated account can join a group DM and read the entire private message history, leading to the leakage of other users' private conversations. Integrity: An attacker can impersonate participants by sending messages, compromising the integrity of the conversation. Availability: Attackers can force-add third-party users to group DMs without their consent, leading to harassment or unnecessary exposure. Remediation Recommendations Immediate Fix: Add authorization checks to the endpoint to ensure only the owner or existing members of a group DM can add new members. Long-term Measure: Conduct a comprehensive authorization check audit on all endpoints involving user permissions to prevent similar authorization vulnerabilities.

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Discord BOLA Vulnerability: Unauthorized Addition to Group DMs via Missing Authorization Check on PUT Endpoint

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