# CVE-2020-1628: Junos OS: EX4300: Traffic from the network internal to the device (128.0.0.0) may be forwarded to egress interfaces

> Internal traffic from the Routing Engine may leak configuration details and kernel versions to external networks on Juniper EX4300 switches.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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:** 8 Apr 2020
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-63wf-3ch2-x4r5

## What is CVE-2020-1628?

CVE-2020-1628 is a medium-severity vulnerability in Juniper Junos, published on 8 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Juniper Networks Junos OS uses the 128.0.0.0/2 subnet for internal communications between the RE and PFEs. It was discovered that packets utilizing these IP addresses may egress an EX4300 switch, leaking configuration information such as heartbeats, kernel versions, etc. out to the Internet, leading to an information exposure vulnerability. This issue affects Juniper Networks Junos OS: 14.1X53 versions prior to 14.1X53-D53 on EX4300; 15.1 versions prior to 15.1R7-S6 on EX4300; 15.1X49 versions prior to 15.1X49-D200, 15.1X49-D210 on EX4300; 16.1 versions prior to 16.1R7-S7 on EX4300; 17.1 versions prior to 17.1R2-S11, 17.1R3-S2 on EX4300; 17.2 versions prior to 17.2R3-S3 on EX4300; 17.3 versions prior to 17.3R2-S5, 17.3R3-S7 on EX4300; 17.4 versions prior to 17.4R2-S9, 17.4R3 on EX4300; 18.1 versions prior to 18.1R3-S8 on EX4300; 18.2 versions prior to 18.2R3-S2 on EX4300; 18.3 versions prior to 18.3R2-S3, 18.3R3, 18.3R3-S1 on EX4300; 18.4 versions prior to 18.4R1-S5, 18.4R2-S3, 18.4R3 on EX4300; 19.1 versions prior to 19.1R1-S4, 19.1R2 on EX4300; 19.2 versions prior to 19.2R1-S4, 19.2R2 on EX4300; 19.3 versions prior to 19.3R1-S1, 19.3R2 on EX4300.

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2020-1628?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2020-1628?

No fix has been published for CVE-2020-1628 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-1628 being exploited?

There is no known exploitation of CVE-2020-1628 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-2020-1628 and fix it if it is affected.

What it is: CVE-2020-1628 is a medium-severity vulnerability in Juniper Junos, published on 8 Apr 2020. 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-2020-1628 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-2020-1628/ (Markdown: https://insights.sbomify.com/CVE-2020-1628/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1628
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1628
- OSV: https://osv.dev/vulnerability/CVE-2020-1628

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-1628/
Summaries are generated and may contain mistakes; the official description above is the record.