What is CVE-2026-102253?

CVE-2026-102253 is a high-severity vulnerability in Esnet Iperf3, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 7.5/10. Published 2026-09-29.

How severe is CVE-2026-102253?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Esnet Iperf3

CVE-2026-102253

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.

Published 2026-09-29.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Esnet Iperf3

Weakness classification (CWE)

CWE-835 — Loop with Unreachable Exit Condition (Infinite Loop)

References

github.com/esnet/iperf/releases/tag/3.22 (vendor-advisory, patch)
github.com/esnet/iperf/blob/master/RELNOTES.md (release-notes)
www.vulncheck.com/advisories/iperf3-udp-receive-worker-infinite-loop-dos (third-party-advisory)

Frequently asked questions

What is CVE-2026-102253?: CVE-2026-102253 is a high-severity vulnerability in Esnet Iperf3, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 7.5/10. Published 2026-09-29.
How severe is CVE-2026-102253?: High severity. CVSS v3 base score is 7.5 out of 10.