# CVE-2026-101283: iperf3 heap buffer overflow in RSA decryption

Source: https://junglewise.ai/threats/cve-2026-101283-iperf3-3-20-3-21-esnet-iperf-has-a-pre-auth-heap-buffer-overflow  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-30. Updated: 2026-10-05  
License: CC BY 4.0 with a link back

CVE-2026-101283 · Severity: info · Published 2026-09-30

iperf3 is a network performance testing tool used to measure bandwidth and latency. An unauthenticated attacker can send a specially crafted authentication request to trigger a heap buffer overflow, potentially crashing the iperf3 server or enabling remote code execution.

Technologies: [ESnet Iperf3](https://junglewise.ai/threats/technologies/esnet-iperf3). Vendors: [ESnet](https://junglewise.ai/threats/vendors/esnet).

## Quick answers

**Is CVE-2026-101283 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-101283 being exploited in the wild.

**How severe is CVE-2026-101283?** Informational severity, published 30 September 2026.

**Which products and versions are affected?** ESnet Iperf3 3.20–3.21.

**Is there a fix for CVE-2026-101283?** Yes: fixed in 3.22. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-101283 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-101283?** 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.

## How to fix

- Fixed in 3.22

## Technical details

A pre-authentication heap buffer overflow exists in the decrypt_rsa_message() function where a 256-byte RSA buffer is read with an attacker-controlled ciphertext length, allowing an unauthenticated remote client to overflow the heap via an oversized authtoken. The vulnerability is triggered during the authentication handshake before any credentials are validated, and network-based exploitation is possible.

## Affected products

- esnet iperf3 3.20–3.21

## References

- [https://newreleases.io/project/github/esnet/iperf/release/3.22](https://newreleases.io/project/github/esnet/iperf/release/3.22)

## Related threats

- [iperf3 heap use-after-free in server watchdog timer](https://junglewise.ai/threats/cve-2026-101276-iperf3-3-21-esnet-iperf-contains-a-remote-unauthenticated-heap)
- [iperf3 denial of service in UDP receive worker](https://junglewise.ai/threats/cve-2026-102253-iperf3-versions-prior-to-3-22-contains-a-denial-of-service)