# CVE-2026-102253: iperf3 < 3.22 UDP Receive Worker Infinite Loop DoS

> Remote attackers can cause a permanent denial of service in iperf3 servers by triggering an infinite loop in the UDP receive worker with crafted packets.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Sep 2026
- **Updated:** 1 Oct 2026
- **Also known as:** ALSA-2026:88207, AZL-105051, BELL-CVE-2026-102253, DEBIAN-CVE-2026-102253, GHSA-jhpr-vprv-wh8f, MINI-r7jc-pp9j-682p, RLSA-2026:88207, UBUNTU-CVE-2026-102253

## What is CVE-2026-102253?

CVE-2026-102253 is a high-severity denial of service vulnerability in esnet iperf3, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

iperf3 versions prior to 3.22 contains a denial of service vulnerability that allows unauthenticated remote attackers to crash-loop the server's UDP receive worker into an unrecoverable infinite loop by sending a single crafted control-channel parameter message followed by one 16-byte UDP datagram. Attackers can permanently pin the affected per-stream receive thread at approximately 100% CPU usage, rendering the server unusable until forcibly killed with SIGKILL, as the process does not respond to normal control-channel closure.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-102253?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `iperf3` | AlmaLinux:10 | All versions | 3.17.1-6.el10_2.2 |
| `iperf3` | Rocky Linux:10 | All versions | 0:3.17.1-6.el10_2.2 |

## How do I fix CVE-2026-102253?

Upgrade to a fixed version.

## Is CVE-2026-102253 being exploited?

There is no known exploitation of CVE-2026-102253 in the wild and no public exploit code.

Public exploit code:

- DOS infinite-loop Vulnerability POC (github_poc): https://github.com/Ravi-lk/CVE-2026-102253-POC

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-102253 and fix it if it is affected.

What it is: CVE-2026-102253 is a high-severity denial of service vulnerability in esnet iperf3, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-102253 in the wild and no public exploit code.

Affected product: esnet iperf3. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-102253/ (Markdown: https://insights.sbomify.com/CVE-2026-102253/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-102253
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-102253
- OSV: https://osv.dev/vulnerability/CVE-2026-102253

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-102253/
Summaries are generated and may contain mistakes; the official description above is the record.