What’s Vulnerable › Vulnerabilities

CVE-2026-102253: iperf3 < 3.22 UDP Receive Worker Infinite Loop DoS

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-29 · updated 2026-09-30
• Weakness: CWE-835

Description

iperf3 versions prior to 3.22 contains a denial of service vulnerability that allows unauthenticated remote attackers to crash-loop the server's UDP receive worker into an unrecoverable infinite loop by sending a single crafted control-channel parameter message followed by one 16-byte UDP datagram. Attackers can permanently pin the affected per-stream receive thread at approximately 100% CPU usage, rendering the server unusable until forcibly killed with SIGKILL, as the process does not respond to normal control-channel closure.

Affected products

• esnet iperf3: from 3.14 before 3.22 — fixed in 3.22

How to fix

Upgrade to a fixed version: esnet iperf3 3.22. Check the vendor advisory for mitigations.

References

• https://github.com/esnet/iperf/blob/master/RELNOTES.md
• https://github.com/esnet/iperf/releases/tag/3.22
• https://www.vulncheck.com/advisories/iperf3-udp-receive-worker-infinite-loop-dos

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