# CVE-2021-0225: Junos OS Evolved: Stateless IP firewall filter does not work as expected

> Stateless IP firewall filters using policer actions may fail to apply, allowing unauthorized traffic to bypass security controls on Juniper devices.

- **Severity:** Medium 5.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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:** 22 Apr 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-v55m-mm25-x584

## What is CVE-2021-0225?

CVE-2021-0225 is a medium-severity vulnerability in Juniper Junos Os Evolved, published on 22 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An Improper Check for Unusual or Exceptional Conditions in Juniper Networks Junos OS Evolved may cause the stateless firewall filter configuration which uses the action 'policer' in certain combinations with other options to not take effect. An administrator can use the following CLI command to see the failures with filter configuration: user@device> show log kfirewall-agent.log | match ERROR Jul 23 14:16:03 ERROR: filter not supported This issue affects Juniper Networks Junos OS Evolved: Versions 19.1R1-EVO and above prior to 20.3R1-S2-EVO, 20.3R2-EVO. This issue does not affect Juniper Networks Junos OS.

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

## Which versions are affected by CVE-2021-0225?

It affects 1 product.


Products: Juniper Junos Os Evolved.

## How do I fix CVE-2021-0225?

No fix has been published for CVE-2021-0225 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-0225 being exploited?

There is no known exploitation of CVE-2021-0225 in the wild and no public exploit code.

## Other vulnerabilities in Juniper Junos Os Evolved

- [CVE-2026-21902](https://insights.sbomify.com/CVE-2026-21902/): Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root (critical 9.3)
- [CVE-2023-28983](https://insights.sbomify.com/CVE-2023-28983/): Junos OS Evolved: Shell Injection vulnerability in the gNOI server (high 8.8)
- [CVE-2025-21599](https://insights.sbomify.com/CVE-2025-21599/): Denial of service in Junos OS Evolved (high 8.7)
- [CVE-2024-47502](https://insights.sbomify.com/CVE-2024-47502/): Junos OS Evolved: TCP session state is not always cleared on the Routing Engine leading to DoS (high 8.7)
- [CVE-2024-39531](https://insights.sbomify.com/CVE-2024-39531/): Junos OS Evolved: ACX 7000 Series: Protocol specific DDoS configuration affects other protocols (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-0225 and fix it if it is affected.

What it is: CVE-2021-0225 is a medium-severity vulnerability in Juniper Junos Os Evolved, published on 22 Apr 2021. 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-2021-0225 in the wild and no public exploit code.

Affected product: Juniper Junos Os Evolved. 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-2021-0225/ (Markdown: https://insights.sbomify.com/CVE-2021-0225/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-0225
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-0225
- OSV: https://osv.dev/vulnerability/CVE-2021-0225

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-0225/
Summaries are generated and may contain mistakes; the official description above is the record.