# CVE-2024-21596: Memory corruption in Junos OS

> An unauthenticated attacker can cause a denial of service on the backup Routing Engine by sending a specific BGP UPDATE message to devices with NSR enabled.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Jan 2024
- **Updated:** 25 Sep 2024
- **Also known as:** GHSA-rj2r-9q5p-4c4w

## What is CVE-2024-21596?

CVE-2024-21596 is a medium-severity memory corruption vulnerability in Juniper Junos, published on 12 Jan 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A Heap-based Buffer Overflow vulnerability in the Routing Protocol Daemon (RPD) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, network based attacker to cause a Denial of Service (DoS).

If an attacker sends a specific BGP UPDATE message to the device, this will cause a memory overwrite and therefore an RPD crash and restart in the backup Routing Engine (RE). Continued receipt of these packets will cause a sustained Denial of Service (DoS) condition in the backup RE.

The primary RE is not impacted by this issue and there is no impact on traffic.

This issue only affects devices with NSR enabled.

Note: NSR is not supported on the SRX Series and is therefore not affected by this vulnerability.
This issue requires an attacker to have an established BGP session to a system affected by the issue. This issue affects both eBGP and iBGP implementations.

This issue affects:

Juniper Networks Junos OS

  *  All versions earlier than 20.4R3-S9;
  *  21.2 versions earlier than 21.2R3-S7;
  *  21.3 versions earlier than 21.3R3-S5;
  *  21.4 versions earlier than 21.4R3-S5;
  *  22.1 versions earlier than 22.1R3-S4;
  *  22.2 versions earlier than 22.2R3-S2;
  *  22.3 versions earlier than 22.3R3-S1;
  *  22.4 versions earlier than 22.4R2-S2, 22.4R3;
  *  23.1 versions earlier than 23.1R2;
  *  23.2 versions earlier than 23.2R1-S2, 23.2R2.

Juniper Networks Junos OS Evolved

  *  All versions earlier than 21.3R3-S5-EVO;
  *  21.4-EVO versions earlier than 21.4R3-S5-EVO;
  *  22.1-EVO versions earlier than 22.1R3-S4-EVO;
  *  22.2-EVO versions earlier than 22.2R3-S2-EVO;
  *  22.3-EVO versions later than 22.3R1-EVO;
  *  22.4-EVO versions earlier than 22.4R2-S2-EVO, 22.4R3-EVO;
  *  23.1-EVO versions earlier than 23.1R2-EVO;
  *  23.2-EVO versions earlier than 23.2R1-S2-EVO, 23.2R2-EVO.

Weakness: CWE-787 (Out-of-bounds Write), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2024-21596?

It affects 2 products.


Products: Juniper Junos, Juniper Junos Os Evolved.

## How do I fix CVE-2024-21596?

No fix has been published for CVE-2024-21596 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-21596 being exploited?

There is no known exploitation of CVE-2024-21596 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-2024-21596 and fix it if it is affected.

What it is: CVE-2024-21596 is a medium-severity memory corruption vulnerability in Juniper Junos, published on 12 Jan 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-2024-21596 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-2024-21596/ (Markdown: https://insights.sbomify.com/CVE-2024-21596/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-21596
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-21596
- OSV: https://osv.dev/vulnerability/CVE-2024-21596

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-21596/
Summaries are generated and may contain mistakes; the official description above is the record.