# CVE-2026-71218: Iperf3: unbounded peer-controlled allocation in iperf3 json_read() allows unauthenticated remote memory exhaustion

CVE-2026-71218 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-71218, released August 13, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-71218
- Priority: Routine
- CVSS: 5.3 (Moderate)
- EPSS: 0.0038
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 11, 2026
- Weakness: Memory Allocation with Excessive Size Value
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-71218

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | iperf opensuse-leap 16.0 | 3.21-160000.1.1 | [OPENSUSE-SU-2026:22090-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22090-1.md) | Nov 7, 2026 |
| Linux | iperf sles 15.7 | 3.22-150000.3.18.1 | [SUSE-SU-2026:4678-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4678-1.md) | Nov 7, 2026 |
| Linux | iperf sles 16.0 | 3.21-160000.1.1 | [SUSE-SU-2026:24234-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24234-1.md) | Nov 7, 2026 |
| Linux | iperf3 Debian 13.5 (trixie) | 3.18-1 | [DEBIAN-CVE-2026-71218](https://patchblox.com/security/data/fix/linux/debian-cve-2026-71218.md) | Aug 13, 2026 |
| Linux | iperf3 Debian 14 | 3.18-1 | [DEBIAN-CVE-2026-71218](https://patchblox.com/security/data/fix/linux/debian-cve-2026-71218.md) | Aug 13, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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