CVE-2026-101276: Esnet IPERF3

Critical severity, CVSS 9.2. EPSS: 0.4% chance of exploitation in the next 30 days.

iperf3 3.21 (esnet/iperf) contains a remote, unauthenticated heap use-after-free: the server's per-test watchdog server_timer_proc() frees streams without cancelling/joining their worker threads, so a blocked worker dereferences a freed iperf_stream; fixed in 3.22.

Affected products

• Esnet IPERF3: version 3.21 only

Published 2026-09-30. Last modified 2026-10-01.