# CVE-2024-21607: Security feature bypass in Junos OS

> An attacker can bypass IPv6 firewall filters configured with tcp-reset and payload-protocol, causing packets to be accepted instead of rejected.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **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:** 17 Jun 2025
- **Also known as:** GHSA-84c9-gp6c-qg45

## What is CVE-2024-21607?

CVE-2024-21607 is a medium-severity 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

An Unsupported Feature in the UI vulnerability in Juniper Networks Junos OS on MX Series and EX9200 Series allows an unauthenticated, network-based attacker to cause partial impact to the integrity of the device.

If the "tcp-reset" option is added to the "reject" action in an IPv6 filter which matches on "payload-protocol", packets are permitted instead of rejected. This happens because the payload-protocol match criteria is not supported in the kernel filter causing it to accept all packets without taking any other action. As a fix the payload-protocol match will be treated the same as a "next-header" match to avoid this filter bypass.

This issue doesn't affect IPv4 firewall filters.

This issue affects Juniper Networks Junos OS on MX Series and EX9200 Series:

  *  All versions earlier than 20.4R3-S7;
  *  21.1 versions earlier than 21.1R3-S5;
  *  21.2 versions earlier than 21.2R3-S5;
  *  21.3 versions earlier than 21.3R3-S4;
  *  21.4 versions earlier than 21.4R3-S4;
  *  22.1 versions earlier than 22.1R3-S2;
  *  22.2 versions earlier than 22.2R3-S2;
  *  22.3 versions earlier than 22.3R2-S2, 22.3R3;
  *  22.4 versions earlier than 22.4R1-S2, 22.4R2-S2, 22.4R3.

Weakness: CWE-447 (Unimplemented or Unsupported Feature in UI)

## Which versions are affected by CVE-2024-21607?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2024-21607?

No fix has been published for CVE-2024-21607 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-21607 being exploited?

There is no known exploitation of CVE-2024-21607 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-2024-21607 and fix it if it is affected.

What it is: CVE-2024-21607 is a medium-severity 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-2024-21607 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-2024-21607/ (Markdown: https://insights.sbomify.com/CVE-2024-21607/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-21607
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-21607
- OSV: https://osv.dev/vulnerability/CVE-2024-21607

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-21607/
Summaries are generated and may contain mistakes; the official description above is the record.