CVE-2026-67199 is a denial of service vulnerability in perspective versions up to and including 5.0.0. Attackers can craft expressions containing unbounded for or while loops embedded in a TableMakeViewReq message. These expressions include arbitrarily large iteration counts evaluated once per table row, which blocks the Tornado IOLoop without any limits or cancellation mechanisms. This results in the server event loop being blocked indefinitely, rendering the server unresponsive to all connected clients.

Successful exploitation causes a denial of service by blocking the server event loop indefinitely. This prevents the server from processing any further requests, effectively making the service unavailable to all users. There is no indication of privilege escalation or data compromise from the provided information.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary mitigation has been documented in the provided data. Until a patch is available, users should consider restricting or validating input expressions to prevent unbounded loops if possible.