CVE-2026-71218
Iperf3: unbounded peer-controlled allocation in iperf3 json_read() allows unauthenticated remote memory exhaustion
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.
Fixes and workarounds
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.
Source: CNA: redhatAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| Red Hat Enterprise Linux 10 Red Hat iperf3
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 7 Red Hat iperf3
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 8 Red Hat iperf3
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 9 Red Hat iperf3
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 5.3 medium |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L | CNA: redhat |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://access.redhat.com/security/cve/CVE-2026-71218CNA: redhat · vdb-entry, x_refsource_REDHAT
- https://bugzilla.redhat.com/show_bug.cgi?id=2463003CNA: redhat · issue-tracking, x_refsource_REDHAT
- https://github.com/esnet/iperf/commit/0128d0357b7e8916fe39e980e455729bc0e5fd4eCNA: redhat
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