Fleet and Elastic Agent 8.19.21

IMPORTANT: This documentation is no longer updated. Refer to Elastic's version policy and the latest documentation.

The 8.19.21 release contains fixes for potential security vulnerabilities. For details, go to the security announcements.

Fix local privilege escalation via binary tampering on Windows unprivileged installs. #16058

Update Go to 1.26.6. #7644 #16203
Prevent ghost agent documents caused by concurrent enrollment retries. #7662
Bump github.com/kardianos/service to v1.3.0 and update Linux systemd template for new mini template engine. #15976

Reject stale policy revisions before secret resolution in the policy monitor. #7572 #7570
Read cgroup memory limit for cache sizing when GOMEMLIMIT is not set. #7573
Fix Windows FIPS upgrade failure caused by mismatched directory name. #16065
Align OTel Elasticsearch exporter request and document retry behavior with Beats Elasticsearch output. #16089 #14531
Allow the current Windows Agent user to write component executables. #16173
Diagnostics now collects component trace logs in container deployments. #16177