# CVE-2024-21603: Junos OS: MX Series: Gathering statistics in a scaled SCU/DCU configuration will lead to a device crash

> A network-based attacker with low privileges can cause a device crash and sustained denial of service on specific Juniper MX Series devices by triggering kernel exceptions during statistics gathering.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Jan 2024
- **Updated:** 17 Jun 2025
- **Also known as:** GHSA-f572-5hm8-87qp

## What is CVE-2024-21603?

CVE-2024-21603 is a medium-severity denial of service vulnerability in Juniper Junos, published on 12 Jan 2024. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

An Improper Check for Unusual or Exceptional Conditions vulnerability in the kernel of Juniper Network Junos OS on MX Series allows a network based attacker with low privileges to cause a denial of service.

If a scaled configuration for Source class usage (SCU) / destination class usage (DCU) (more than 10 route classes) is present and the SCU/DCU statistics are gathered by executing specific SNMP requests or CLI commands, a 'vmcore' for the RE kernel will be seen which leads to a device restart. Continued exploitation of this issue will lead to a sustained DoS.

This issue only affects MX Series devices with MPC10, MPC11 or LC9600, and MX304. No other MX Series devices are affected.

This issue affects Juniper Networks Junos OS:

  *  All versions earlier than 20.4R3-S9;
  *  21.2 versions earlier than 21.2R3-S6;
  *  21.3 versions earlier than 21.3R3-S5;
  *  21.4 versions earlier than 21.4R3;
  *  22.1 versions earlier than 22.1R3;
  *  22.2 versions earlier than 22.2R2;
  *  22.3 versions earlier than 22.3R2.

Weakness: CWE-754 (Improper Check for Unusual or Exceptional Conditions)

## Which versions are affected by CVE-2024-21603?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2024-21603?

No fix has been published for CVE-2024-21603 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-21603 being exploited?

There is no known exploitation of CVE-2024-21603 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-2024-21603 and fix it if it is affected.

What it is: CVE-2024-21603 is a medium-severity denial of service vulnerability in Juniper Junos, published on 12 Jan 2024. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-21603 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-2024-21603/ (Markdown: https://insights.sbomify.com/CVE-2024-21603/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-21603
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-21603
- OSV: https://osv.dev/vulnerability/CVE-2024-21603

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-21603/
Summaries are generated and may contain mistakes; the official description above is the record.