# CVE-2025-52951: Junos OS: IPv6 firewall filter fails to match payload-protocol

> Attackers can bypass IPv6 firewall filters on Junos OS control plane by exploiting a kernel filter processing flaw that ignores payload-protocol matches.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/AU:Y/R:U/RE:M`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 11 Jul 2025
- **Updated:** 15 Jul 2025
- **Also known as:** GHSA-wgx4-f5ch-j468

## What is CVE-2025-52951?

CVE-2025-52951 is a medium-severity vulnerability in Juniper Junos, published on 11 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A Protection Mechanism Failure vulnerability in kernel filter processing of Juniper Networks Junos OS allows an attacker sending IPv6 traffic destined to the device to effectively bypass any firewall filtering configured on the interface.

Due to an issue with Junos OS kernel filter processing, the 'payload-protocol' match is not being supported, causing any term containing it to accept all packets without taking any other action. In essence, these firewall filter terms were being processed as an 'accept' for all traffic on the interface destined for the control plane, even when used in combination with other match criteria.

This issue only affects firewall filters protecting the device's control plane. Transit firewall filtering is unaffected by this vulnerability.

This issue affects Junos OS: 

  *  all versions before 21.2R3-S9, 
  *  from 21.4 before 21.4R3-S11, 
  *  from 22.2 before 22.2R3-S7, 
  *  from 22.4 before 22.4R3-S7, 
  *  from 23.2 before 23.2R2-S4, 
  *  from 23.4 before 23.4R2-S5, 
  *  from 24.2 before 24.2R2-S1, 
  *  from 24.4 before 24.4R1-S2, 24.4R2.

This is a more complete fix for previously published CVE-2024-21607 (JSA75748).

Weakness: CWE-693 (Protection Mechanism Failure)

## Which versions are affected by CVE-2025-52951?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2025-52951?

No fix has been published for CVE-2025-52951 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-52951 being exploited?

There is no known exploitation of CVE-2025-52951 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-2025-52951 and fix it if it is affected.

What it is: CVE-2025-52951 is a medium-severity vulnerability in Juniper Junos, published on 11 Jul 2025. 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-2025-52951 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-2025-52951/ (Markdown: https://insights.sbomify.com/CVE-2025-52951/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-52951
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-52951
- OSV: https://osv.dev/vulnerability/CVE-2025-52951

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-52951/
Summaries are generated and may contain mistakes; the official description above is the record.