PraisonAI is a multi-agent teams system. Prior to praisonai 4.6.58, MCP HTTP Stream _validate_origin uses request_origin.startswith(allowed), allowing the attac…

CVE-2026-55532 affects PraisonAI, a multi-agent teams system, in versions prior to 4.6.58. The vulnerability exists in the MCP HTTP Stream _validate_origin function, which uses a startswith() check to validate request origins against an allowlist. An attacker can craft a malicious origin such as localhost.attacker.com that satisfies the localhost allowlist check due to the flawed string prefix matching. This allows cross-origin requests to be sent without CORS preflight by using Content-Type: text/plain, enabling unauthenticated access to the tools/call API endpoint without an API key. Successful exploitation can lead to unauthorized file writes that persist malicious agent instructions, potentially compromising the integrity of AI agent behavior. The vulnerability has been patched in PraisonAI version 4.6.58.