CVE-2026-71218

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

Published Aug 11, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

Vendor Workaround

To mitigate this issue, restrict network access to the `iperf3` control port, ensuring it is only reachable by trusted clients. This can be achieved by configuring firewall rules to limit inbound connections to the `iperf3` service. Additionally, consider running the `iperf3` service within environments that enforce process or container memory limits to further contain potential resource exhaustion. Note that authentication alone is insufficient as the memory allocation occurs before authentication checks.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Redhat rhel Els
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
cpe:/a:redhat:enterprise_linux:10
cpe:/a:redhat:enterprise_linux:8
cpe:/a:redhat:enterprise_linux:9
cpe:/o:redhat:rhel_els:7
Vendors & Products Redhat rhel Els
Type Values Removed Values Added
First Time appeared Iperf3 Project
Iperf3 Project iperf3
Vendors & Products Iperf3 Project
Iperf3 Project iperf3
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Iperf3: unbounded peer-controlled allocation in iperf3 json_read() allows unauthenticated remote memory exhaustion
First Time appeared Redhat
Redhat enterprise Linux
Weaknesses CWE-789
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Nov 5, 2026, 10:52 PM
Reserved
Aug 5, 2026, 8:41 AM
Status
Awaiting Analysis
Published
Aug 11, 2026, 9:17 AM
Modified
Nov 5, 2026, 11:16 PM
Severity
Moderate
Public date
Aug 11, 2026, 8:13 AM