CVE-2026-71218 Iperf3: unbounded peer-controlled allocation in iperf3 json_read() allows unauthenticated remote memory exhaustion
Remote attackers can cause denial of service in iperf3 by triggering unbounded memory allocation via crafted JSON messages.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-71218?
CVE-2026-71218 is a medium-severity denial of service vulnerability in Red Hat Enterprise Linux 10, published on 11 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-789
Which versions are affected by CVE-2026-71218?
How do I fix CVE-2026-71218?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-71218 being exploited?
There is no known exploitation of CVE-2026-71218 in the wild and no public exploit code.
Sources
Also known as AZL-95598, BELL-CVE-2026-71218, DEBIAN-CVE-2026-71218, GHSA-8m2w-v7g5-76v3, UBUNTU-CVE-2026-71218.