danmu_api before 1.21.7 contains an authentication bypass vulnerability that allows unauthenticated attackers to modify server environment configuration when the default TOKEN is used and ADMIN_TOKEN is unset. Attackers can send POST requests to /api/env/set, /api/env/add, or /api/env/del to set ADMIN_TOKEN, lock out operators, redirect OTHER_SERVER or PROXY_URL for SSRF, and trigger redeployment.