# CVE-2026-71217: Denial of service in Red Hat Enterprise Linux 10

> Remote attackers can cause denial of service on iperf3 servers by sending oversized JSON parameters that trigger resource exhaustion.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Aug 2026
- **Updated:** 31 Aug 2026
- **Also known as:** ALSA-2026:61257, ALSA-2026:61389, ALSA-2026:61680, AZL-95601, BELL-CVE-2026-71217, CLSA-2026-1788532080, CLSA-2026-1788821988, DEBIAN-CVE-2026-71217, GHSA-4jvc-h3x3-w6qj, OESA-2026-3527, RHSA-2026:61257, RHSA-2026:61389, RHSA-2026:61680, RLSA-2026:61257, RLSA-2026:61389, RLSA-2026:61680, UBUNTU-CVE-2026-71217

## What is CVE-2026-71217?

CVE-2026-71217 is a high-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 attacker can exploit this vulnerability by sending crafted control-channel JSON with oversized numeric parameters, such as `parallel` and `len`, which are not properly validated by the server. This improper input validation can lead to excessive stream and thread creation, as well as large buffer allocations, causing resource exhaustion. Consequently, this can result in a Denial of Service (DoS) on the affected iperf3 server.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-71217?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `iperf3` | AlmaLinux:10 | All versions | 3.17.1-6.el10_2.1 |
| `iperf3` | AlmaLinux:8 | All versions | 3.5-12.el8_10.1 |
| `iperf3` | AlmaLinux:9 | All versions | 3.9-17.el9_8.1 |
| `iperf3` | Red Hat:enterprise_linux:10.2 | All versions | 0:3.17.1-6.el10_2.1 |
| `iperf3-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 0:3.17.1-6.el10_2.1 |
| `iperf3-debugsource` | Red Hat:enterprise_linux:10.2 | All versions | 0:3.17.1-6.el10_2.1 |
| `iperf3` | Red Hat:enterprise_linux:8::appstream | All versions | 0:3.5-12.el8_10.1 |
| `iperf3-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 0:3.5-12.el8_10.1 |
| `iperf3-debugsource` | Red Hat:enterprise_linux:8::appstream | All versions | 0:3.5-12.el8_10.1 |
| `iperf3` | Red Hat:enterprise_linux:9::appstream | All versions | 0:3.9-17.el9_8.1 |
| `iperf3-debuginfo` | Red Hat:enterprise_linux:9::appstream | All versions | 0:3.9-17.el9_8.1 |
| `iperf3-debugsource` | Red Hat:enterprise_linux:9::appstream | All versions | 0:3.9-17.el9_8.1 |
| `iperf3` | Rocky Linux:10 | All versions | 0:3.17.1-6.el10_2.1 |
| `iperf3` | Rocky Linux:8 | All versions | 0:3.5-12.el8_10.1 |
| `iperf3` | Rocky Linux:9 | All versions | 0:3.9-17.el9_8.1 |

## How do I fix CVE-2026-71217?

Apply the vendor's patch.

## Is CVE-2026-71217 being exploited?

There is no known exploitation of CVE-2026-71217 in the wild and no public exploit code.

Public exploit code:

- A PoC for CVE-2026-71217 (github_poc): https://github.com/Reelix/CVE-2026-71217-PoC

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-71217 and fix it if it is affected.

What it is: CVE-2026-71217 is a high-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.
Exploitation: There is no known exploitation of CVE-2026-71217 in the wild and no public exploit code.

Affected product: Red Hat Enterprise Linux 10. 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-2026-71217/ (Markdown: https://insights.sbomify.com/CVE-2026-71217/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-71217
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-71217
- OSV: https://osv.dev/vulnerability/CVE-2026-71217

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-71217/
Summaries are generated and may contain mistakes; the official description above is the record.