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Fencer Vulns
medium 5.3

CVE-2026-71218 json

Iperf3: unbounded peer-controlled allocation in iperf3 json_read() allows unauthenticated remote memory exhaustion

published 2026-08-11 2 mo ago modified 2026-11-05 3 d ago also EUVD-2026-55991

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 32%
public exploits
0
none known

Summary

A flaw was found in iperf3. A remote unauthenticated attacker can exploit a vulnerability in the `JSON_read()` function, which accepts a peer-controlled message length and allocates memory without an upper bound. This allows the attacker to trigger excessive memory consumption, leading to a Denial of Service (DoS) through memory exhaustion, severe slowdown, or termination of the iperf3 service.

Patch / fix

  • iperf3 Debian 14, Debian 13 3.18-1

debian advisories DEBIAN-CVE-2026-71218

  • 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 Azure Linux 3.0 3.17.1-5

azure linux advisories AZL-95598

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-2026-71218 updated cvss 5.3

iperf3: Unbounded peer-controlled allocation in iperf3 JSON_read() allows unauthenticated remote memory exhaustion

  • Red Hat Enterprise Linux 7 iperf3 Red Hat Enterprise Linux 8 iperf3 Red Hat Enterprise Linux 9 iperf3 Red Hat Enterprise Linux 10 iperf3
    affected: workaround, no fix available “Fix deferred”

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

0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected products

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

Classification

Weakness
  • CWE-789 Memory Allocation with Excessive Size Value

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.