CVE-2026-61428 describes an authentication bypass vulnerability in MervinPraison's PraisonAI AgentMail product. Versions before 4.6.78 do not verify signatures on incoming webhook messages, enabling unauthenticated attackers to inject arbitrary message.received events. This allows spoofing of sender addresses and bypassing of sender allow/block lists, potentially causing the agent to send replies to attacker-controlled addresses. The vulnerability has a CVSS 4.0 base score of 6.9, indicating a medium severity level. No official patch or remediation guidance is currently available, and no known exploits in the wild have been reported.

An attacker can inject arbitrary messages into the PraisonAI AgentMail webhook interface without authentication, spoofing sender addresses. This bypasses sender allow/block lists and can cause the agent to send replies to attacker-controlled addresses. This may lead to unauthorized message injection and potential misuse of the agent's messaging capabilities.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to the webhook endpoint to trusted sources and monitor for suspicious webhook activity. Implement network-level controls to limit POST requests to the webhook interface from untrusted IPs.