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high · CVSS 7.5

CVE-2026-71217

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

Published 11 Aug 2026 · Source updated 4 Nov 2026 · Retrieved 2026-11-05 00:19 UTC

Statance checks for CVE-2026-71217. Connected servers are checked automatically against the fixed versions their distribution or package ecosystem has published for it, including app dependency lockfiles. Check my servers ↗
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What happened?

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.

Description supplied by CVE Program. Formatting is simplified; follow the original advisory for full details.

Affected software and versions

Source-provided software and version information
SoftwareVersion informationFixed version
iperf3Red Hatunaffected: 0:3.17.1-6.el10_2.1 to < *See vendor advisory
iperf3Red Hatunaffected: 0:3.5-12.el8_10.1 to < *See vendor advisory
iperf3Red Hatunaffected: 0:3.9-17.el9_8.1 to < *See vendor advisory
iperf3Red HatDefault status: affectedSee vendor advisory

Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.

Is it being exploited?

This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.

CISA data retrieved 2026-11-06 16:38 UTC. Check CISA ↗

How to respond

  1. Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
  2. Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
  3. Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.

Sources and remediation references

This public advisory does not determine whether a particular server is affected. Records are refreshed as sources change; verify urgent decisions against the original advisory.

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