CVE-2026-61435 is an authentication bypass vulnerability in MervinPraison's PraisonAI product prior to version 4.6.78. When the configuration PRAISONAI_CALL_AUTH=disabled is enabled, the system attempts to restrict access to localhost only by checking the bind host derived from the HTTP Host header. However, since this header is client-controlled, a remote unauthenticated attacker can spoof it to appear as localhost (127.0.0.1), thereby bypassing the restriction. This allows the attacker to list registered agents via GET /api/v1/agents and invoke them via POST /api/v1/agents/{agent_id}/invoke without authentication.

An unauthenticated remote attacker can bypass intended localhost-only restrictions and access sensitive API endpoints to list and invoke agents. This could lead to unauthorized execution of agent functions, potentially compromising system integrity or confidentiality depending on agent capabilities.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid setting PRAISONAI_CALL_AUTH=disabled or restrict network access to the service to trusted hosts only to prevent exploitation via spoofed Host headers.