Quick answers
- Is CVE-2026-101276 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-101276 being exploited in the wild.
- How severe is CVE-2026-101276?
- Informational severity, published 30 September 2026.
- Which products and versions are affected?
- ESnet Iperf3 3.21.
- Is there a fix for CVE-2026-101276?
- A patch was published on 2026-09-29: fixed in version 3.22 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-101276 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-101276?
- Check whether you run ESnet Iperf3 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The server_timer_proc() watchdog function frees stream structures without properly cancelling or joining their associated worker threads, allowing blocked workers to dereference freed memory. This is a remote, unauthenticated heap use-after-free vulnerability accessible over the network. The fix in 3.22 ensures proper thread synchronization before freeing stream resources.
Affected products
- esnet iperf3 3.21
Timeline
- 2026-09-30: disclosed
- 2026-09-29: patched: fixed in version 3.22