# CVE-2024-39562: Junos OS Evolved: A high rate of SSH connections causes a Denial of Service

> An unauthenticated attacker can cause a Denial of Service by flooding SSH connections, crashing xinetd and blocking legitimate SSH access on Junos OS Evolved devices.

- **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:** No
- **Published:** 10 Jul 2024
- **Updated:** 2 Aug 2024
- **Also known as:** GHSA-8j3v-w6gq-fj6q

## What is CVE-2024-39562?

CVE-2024-39562 is a high-severity denial of service vulnerability in Juniper Junos Os Evolved, published on 10 Jul 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A Missing Release of Resource after Effective Lifetime vulnerability the xinetd process, responsible for spawning SSH daemon (sshd) instances, of Juniper Networks Junos OS Evolved allows an unauthenticated network-based attacker to cause a Denial of Service (DoS) by blocking SSH access for legitimate users.  Continued receipt of these connections will create a sustained Denial of Service (DoS) condition.

The issue is triggered when a high rate of concurrent SSH requests are received and terminated in a specific way, causing xinetd to crash, and leaving defunct sshd processes. Successful exploitation of this vulnerability blocks both SSH access as well as services which rely upon SSH, such as SFTP, and Netconf over SSH.

Once the system is in this state, legitimate users will be unable to SSH to the device until service is manually restored.  See WORKAROUND section below.

Administrators can monitor an increase in defunct sshd processes by utilizing the CLI command:

  > show system processes | match sshd
  root     25219 30901  0 Jul16 ?        00:00:00 [sshd] <defunct>

This issue affects Juniper Networks Junos OS Evolved:
  *  All versions prior to 21.4R3-S7-EVO
  *  22.3-EVO versions prior to 22.3R2-S2-EVO, 22.3R3-S2-EVO;
  *  22.4-EVO versions prior to 22.4R3-EVO;
  *  23.2-EVO versions prior to 23.2R2-EVO.

This issue does not affect Juniper Networks Junos OS Evolved 22.1-EVO nor 22.2-EVO.

Weakness: CWE-772 (Missing Release of Resource after Effective Lifetime)

## Which versions are affected by CVE-2024-39562?

It affects 1 product.


Products: Juniper Junos Os Evolved.

## How do I fix CVE-2024-39562?

No fix has been published for CVE-2024-39562 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-39562 being exploited?

There is no known exploitation of CVE-2024-39562 in the wild and no public exploit code.

## Other vulnerabilities in Juniper Junos Os Evolved

- [CVE-2026-21902](https://insights.sbomify.com/CVE-2026-21902/): Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root (critical 9.3)
- [CVE-2023-28983](https://insights.sbomify.com/CVE-2023-28983/): Junos OS Evolved: Shell Injection vulnerability in the gNOI server (high 8.8)
- [CVE-2025-21599](https://insights.sbomify.com/CVE-2025-21599/): Denial of service in Junos OS Evolved (high 8.7)
- [CVE-2024-47502](https://insights.sbomify.com/CVE-2024-47502/): Junos OS Evolved: TCP session state is not always cleared on the Routing Engine leading to DoS (high 8.7)
- [CVE-2024-39531](https://insights.sbomify.com/CVE-2024-39531/): Junos OS Evolved: ACX 7000 Series: Protocol specific DDoS configuration affects other protocols (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-39562 and fix it if it is affected.

What it is: CVE-2024-39562 is a high-severity denial of service vulnerability in Juniper Junos Os Evolved, published on 10 Jul 2024. 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-2024-39562 in the wild and no public exploit code.

Affected product: Juniper Junos Os Evolved. 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-2024-39562/ (Markdown: https://insights.sbomify.com/CVE-2024-39562/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-39562
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-39562
- OSV: https://osv.dev/vulnerability/CVE-2024-39562

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From sbomify Insights: https://insights.sbomify.com/CVE-2024-39562/
Summaries are generated and may contain mistakes; the official description above is the record.