# CVE-2024-21605: Junos OS: SRX 300 Series: Specific link local traffic causes a control plane overload

> An unauthenticated adjacent attacker can cause a denial of service on Juniper SRX 300 Series devices by sending specific link-local traffic to the control plane.

- **Severity:** High 7.1 (`CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Apr 2024
- **Updated:** 9 Aug 2024
- **Also known as:** GHSA-24g5-r7q6-hhmg

## What is CVE-2024-21605?

CVE-2024-21605 is a high-severity denial of service vulnerability in Juniper Junos, published on 12 Apr 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An Exposure of Resource to Wrong Sphere vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on SRX 300 Series allows an unauthenticated, adjacent attacker to cause a Denial of Service (DoS).

Specific valid link-local traffic is not blocked on ports in STP blocked state but is instead sent to the control plane of the device. This leads to excessive resource consumption and in turn severe impact on all control and management protocols of the device.

This issue affects Juniper Networks Junos OS:
  *  21.2 version 21.2R3-S3 and later versions earlier than 21.2R3-S6;
  *  22.1 version 22.1R3 and later versions earlier than 22.1R3-S4;
  *  22.2 version 

22.2R2

and later versions earlier than 22.2R3-S2;
  *  22.3 version 

22.3R2 

and later versions earlier than 22.3R3-S1;

  *  22.4 versions earlier than 22.4R2-S2, 22.4R3;
  *  23.2 versions earlier than 23.2R1-S1, 23.2R2.

This issue does not affect Juniper Networks Junos OS 21.4R1 and later versions of 21.4.

Weakness: CWE-668 (Exposure of Resource to Wrong Sphere)

## Which versions are affected by CVE-2024-21605?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2024-21605?

No fix has been published for CVE-2024-21605 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-21605 being exploited?

There is no known exploitation of CVE-2024-21605 in the wild and no public exploit code.

## Other vulnerabilities in Juniper Junos

- [CVE-2023-36845](https://insights.sbomify.com/CVE-2023-36845/): Juniper Junos OS EX Series and SRX Series PHP External Variable Modification (critical 9.8, exploited in the wild)
- [CVE-2020-1631](https://insights.sbomify.com/CVE-2020-1631/): Juniper Junos OS Path Traversal (high 8.8, exploited in the wild)
- [CVE-2025-21590](https://insights.sbomify.com/CVE-2025-21590/): Juniper Junos OS Improper Isolation or Compartmentalization (medium 6.7, exploited in the wild)
- [CVE-2023-36851](https://insights.sbomify.com/CVE-2023-36851/): Juniper Junos OS SRX Series Missing Authentication for Critical Function (medium 5.3, exploited in the wild)
- [CVE-2023-36844](https://insights.sbomify.com/CVE-2023-36844/): Juniper Junos OS EX Series PHP External Variable Modification (medium 5.3, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-21605 and fix it if it is affected.

What it is: CVE-2024-21605 is a high-severity denial of service vulnerability in Juniper Junos, published on 12 Apr 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-21605 in the wild and no public exploit code.

Affected product: Juniper Junos. 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-2024-21605/ (Markdown: https://insights.sbomify.com/CVE-2024-21605/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-21605
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-21605
- OSV: https://osv.dev/vulnerability/CVE-2024-21605

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-21605/
Summaries are generated and may contain mistakes; the official description above is the record.