stoatchat before 0.15.5 contains an account enumeration vulnerability in the login endpoint that exposes source file locations in error responses. Unauthenticated attackers can distinguish between registered and unregistered email addresses by comparing error location fields returned from POST /api/auth/session/login requests.

stoatchat before 0.15.5 fails to validate that MFA tickets belong to the authenticated user, allowing attackers to bypass MFA by using their own valid ticket with another user's session token. Attackers can obtain a ticket from their own account and use it with a victim's session token to disable TOTP, view recovery codes, or perform other sensitive operations without providing the victim's credentials.

stoatchat versions before 0.15.5 contain a denial of service vulnerability in the acknowledgement worker that processes mass mention messages. Authenticated users can send five crafted role-mention messages to terminate all acknowledgement workers, disabling push notifications and mention badges deployment-wide until the API process restarts.

stoatchat before 0.15.5 fails to enforce account-level attempt limits on MFA login challenges, allowing attackers who know a password to guess TOTP codes with only IP-based rate limiting. Attackers can reuse MFA challenge tickets across multiple failed attempts and distribute guesses across IP addresses to bypass rate limiting and gain account access.

stoatchat before 0.15.0 fails to validate SVG viewBox dimensions in the proxy endpoint, allowing attackers to cause denial of service by memory exhaustion. Attackers can host malicious SVGs with extremely large width and height values and trigger concurrent requests to exhaust available memory across proxy replicas.

stoatchat before 0.15.0 contains a missing authorization vulnerability in the Subscribe message handler that allows authenticated attackers to enumerate members and monitor profile updates of private servers without membership. Attackers can subscribe to any server's member-update topic by sending a Subscribe message with an arbitrary server ID, receiving live UserUpdate events including display names, avatars, and status changes for members they should not have access to.

stoatchat versions before 0.15.0 fail to block the IPv6 unspecified address (::) in the SSRF blocklist, allowing unauthenticated attackers to bypass protections via the /proxy and /embed endpoints. Attackers can craft requests using IPv6 literal syntax to access services on the loopback interface and retrieve sensitive internal content.

stoatchat before 0.15.0 contains a permission bypass vulnerability in the messagefetch route that checks only ViewChannel permission instead of requiring ReadMessageHistory. Attackers with ViewChannel access but ReadMessageHistory denied can retrieve individual message content by ID, bypassing the intended history restriction enforced by bulk read routes.

stoatchat (delta) versions before 20250210-1 (0.8.2) contain a logic error in the query messages route. When fetching messages 'nearby' another message, the database query can be given a message limit of zero, which the database interprets as 'no limit'. A remote unauthenticated attacker can craft nearby message fetch requests to download an entire channel's message history in a single expensive request, and can send many such requests in parallel, resulting in denial of service through resource exhaustion.

stoatchat versions before 0.7.8 fail to enforce account creation restrictions including invite-only mode, email verification, captcha, and shield verification. Attackers can create unlimited accounts with unverified email addresses, increasing denial-of-service risk and compromising service integrity.

stoatchat before 0.14.0 contains a server-side request forgery (SSRF) vulnerability that allows unauthenticated network-accessible attackers to bypass the DNS-based IP blocklist by exploiting incomplete address validation in the urlisblacklisted function, which inspects only the first resolved address while the underlying HTTP client iterates all cached addresses.

stoatchat before 0.13.5 contains an unauthenticated server-side request forgery vulnerability in the /proxy and /embed endpoints that accept arbitrary URLs without DNS resolution filtering or private IP range validation. Attackers can enumerate internal services, fingerprint applications, and reach instance metadata endpoints by supplying malicious URLs or leveraging redirect chains to access internal infrastructure.