CVE-2026-101276 Use after free in iperf3
Remote unauthenticated attackers can trigger a heap use-after-free in iperf3 server, potentially leading to code execution or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-101276?
CVE-2026-101276 is a critical use after free vulnerability in esnet iperf3, published on 30 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-416
Which versions are affected by CVE-2026-101276?
How do I fix CVE-2026-101276?
Upgrade to a fixed version.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-101276 being exploited?
There is no known exploitation of CVE-2026-101276 in the wild and no public exploit code.
Sources
Also known as AZL-105492, BELL-CVE-2026-101276, DEBIAN-CVE-2026-101276, GHSA-pmgg-x2vj-36cv, UBUNTU-CVE-2026-101276.