CVE-2023-49805

Summary

CVE-2023-49805 is a vulnerability in Uptime Kuma, a self-hosted monitoring tool, affecting versions prior to 1.23.9. The issue lies in the application's lack of validation for the source of WebSocket communications using Socket.io. This enables third-party websites to establish connections to the server, bypassing firewall protections and potentially accessing unseen vulnerabilities. The vulnerability does not require user interaction or login credentials, making it particularly dangerous for users with "No-auth" mode configured who rely on reverse proxies or firewalls for protection. In response, Uptime Kuma's developers added verification of the HTTP Origin header in version 1.23.9, denying connections that do not match the Host header by default, and allowing users to override this behavior with the `UPTIME_KUMA_WS_ORIGIN_CHECK=bypass` environment variable.

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