Log4j 2.15 vulnerability CVE-2021-45046 upgraded to a critical severity arbitrary code execution

This advisory warns that multiple Log4j 2 vulnerabilities (CVE-2021-44228 and CVE-2021-45046) enable remote code execution and have been actively exploited; it lists affected versions (2.0-beta9 to 2.15.0 excluding 2.12.2), describes conditions under which 2.15.0 remains exploitable, provides mitigation steps (upgrade to 2.16.0/2.17.x or remove JndiLookup), and includes a timeline of discovery and escalation.