---
id: CVE-2026-101283
title: >-
  iperf3 3.20–3.21 (esnet/iperf) has a pre-auth heap buffer overflow in
  decrypt_rsa_message(): a 256-byte RSA buffer is BIO_read with the
  attacker-controlled ciphertext length (guard warns only), so an
  unauthenticated client overflows the …
summary: >-
  iperf3 3.20–3.21 (esnet/iperf) has a pre-auth heap buffer overflow in
  decrypt_rsa_message(): a 256-byte RSA buffer is BIO_read with the
  attacker-controlled ciphertext length (guard warns only), so an
  unauthenticated client overflows the …
severity: critical
cvss: 9.2
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'
cwe:
  - CWE-122
vendor: esnet
product: iperf3
affected:
  - iperf3 3.20
  - iperf3 3.21
published: '2026-09-30'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T22:16:33.317'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-101283'
references:
  - url: 'https://newreleases.io/project/github/esnet/iperf/release/3.22'
    label: 98a01053-8a31-4f6d-9aa9-252be161adc6
tags:
  - nvd
  - cve.org
cvssSource: cna
ingestedAt: '2026-09-30T22:27:27.820Z'
---

## Overview

iperf3 3.20–3.21 (esnet/iperf) has a pre-auth heap buffer overflow in decrypt_rsa_message(): a 256-byte RSA buffer is BIO_read with the attacker-controlled ciphertext length (guard warns only), so an unauthenticated client overflows the heap via an oversized authtoken; fixed in 3.22

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.