Apache ActiveMQ, one of the most widely used open-source messaging brokers, was recently hit by a severe vulnerability tracked as CVE-2024-30943, enabling unauthenticated remote code execution (RCE) via unsafe Java object deserialization. The flaw exists in the way ActiveMQ processes serialized Java objects sent over the OpenWire protocol. Attackers can craft malicious serialized payloads and deliver them to the broker on the exposed TCP port (typically 61616). Once processed, the payload can execute arbitrary system commands, effectively giving attackers full control of the host. What makes this vulnerability dangerous is its pre-auth nature and the fact that many ActiveMQ instances are directly exposed to the internet in enterprise environments. Exploitation requires no special permissions—just network access and knowledge of the protocol. Researchers have already observed proof-of-concept exploits and even active scanning campaigns targeting this weakness. The fix? Upgrade immediately to a patched version or restrict exposure by enforcing strong network segmentation and using SSL/TLS with authentication. If your system uses ActiveMQ, treat this as a top-priority patch—because once RCE is in play, persistence, lateral movement, and data theft are only a few clicks away.