CVE-2026-71217: Iperf3: iperf3 server accepts unbounded peer-controlled json parameters enabling remote denial of service via resource exhaustion

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-11 · updated 2026-08-31
Weakness: CWE-20

Description

A flaw was found in iperf3. A remote attacker can exploit this vulnerability by sending crafted control-channel JSON with oversized numeric parameters, such as `parallel` and `len`, which are not properly validated by the server. This improper input validation can lead to excessive stream and thread creation, as well as large buffer allocations, causing resource exhaustion. Consequently, this can result in a Denial of Service (DoS) on the affected iperf3 server.

Affected products

Red Hat Enterprise Linux 10: all versions — fixed in 0:3.17.1-6.el10_2.1
Red Hat Enterprise Linux 7: all versions
Red Hat Enterprise Linux 8: all versions — fixed in 0:3.5-12.el8_10.1
Red Hat Enterprise Linux 9: all versions — fixed in 0:3.9-17.el9_8.1

How to fix

Upgrade to a fixed version: Red Hat Enterprise Linux 10 0:3.17.1-6.el10_2.1; Red Hat Enterprise Linux 8 0:3.5-12.el8_10.1; Red Hat Enterprise Linux 9 0:3.9-17.el9_8.1. Check the vendor advisory for mitigations.

References

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