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Fencer Vulns
high 7.5

CVE-2026-71217 json

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

published 2026-08-11 2 mo ago modified 2026-11-05 4 d ago also EUVD-2026-55990

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

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.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 10 0:3.17.1-6.el10_2.1
  • Red Hat Red Hat Enterprise Linux 8 0:3.5-12.el8_10.1
  • Red Hat Red Hat Enterprise Linux 9 0:3.9-17.el9_8.1
  • iperf3 Debian 14 3.22-0.1

debian advisories DEBIAN-CVE-2026-71217

  • iperf3 RHEL 10.2 3.17.1-6.el10_2.1
  • iperf3 RHEL 9 3.9-17.el9_8.1
  • iperf3 RHEL 8 3.5-12.el8_10.1

red hat advisories RHSA-2026:61680RHSA-2026:61389RHSA-2026:61257

  • iperf SLE Module for Package Hub 15 SP7, Enterprise Storage 7.1 3.22-150000.3.18.1
  • iperf SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 3.21-160000.1.1

suse advisories SUSE-SU-2026:4678-1SUSE-SU-2026:24178-1SUSE-SU-2026:24234-1

  • iperf openSUSE Leap 16.0 3.21-160000.1.1
  • iperf openSUSE Tumbleweed 3.22-1.1

opensuse advisories openSUSE-SU-2026:22090-1openSUSE-SU-2026:12060-1

  • iperf3 AlmaLinux 8 3.5-12.el8_10.1
  • iperf3 AlmaLinux 9 3.9-17.el9_8.1
  • iperf3 AlmaLinux 10 3.17.1-6.el10_2.1

almalinux advisories ALSA-2026:61257ALSA-2026:61389ALSA-2026:61680

  • iperf3 Rocky Linux 10 3.17.1-6.el10_2.1
  • iperf3 Rocky Linux 9 3.9-17.el9_8.1
  • iperf3 Rocky Linux 8 3.5-12.el8_10.1

rocky linux advisories RLSA-2026:61680RLSA-2026:61389RLSA-2026:61257

  • iperf3 Azure Linux 3.0 3.17.1-5

azure linux advisories AZL-95601

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-71217 updated cvss 7.5

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

  • Red Hat Enterprise Linux 7 iperf3
    affected: workaround, no fix available
  • Red Hat Enterprise Linux AppStream (v. 8) iperf3 3.5-12.el8_10.1
    fixed: vendor fix RHSA-2026:61257
  • Red Hat Enterprise Linux AppStream (v. 9) iperf3 3.9-17.el9_8.1
    fixed: vendor fix RHSA-2026:61389
  • Red Hat Enterprise Linux AppStream (v. 10) iperf3 3.17.1-6.el10_2.1
    fixed: vendor fix RHSA-2026:61680

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.64% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Enterprise Linux 7

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.