Unpatched Fastjson Vulnerability Exploited in Attacks

Attackers are actively exploiting an unpatched, critical remote code execution vulnerability in the FastJson open-source Java library. The flaw can be exploited without authentication under the library’s stock default configuration, and BleepingComputer reports hackers are already targeting US firms with it. No official patch is available yet — teams running FastJson should review deployment configurations and monitor for exploitation attempts.