# CVE-2020-1626: Junos OS Evolved: Denial of Service vulnerability in processing high rate of specific packets

> An attacker can cause a sustained Denial of Service on Juniper Junos OS Evolved devices by flooding them with specific packets, crashing the packet forwarding process.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **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:** 17 Sep 2024
- **Also known as:** GHSA-5pv5-vwqw-425f

## What is CVE-2020-1626?

CVE-2020-1626 is a high-severity denial of service vulnerability in Juniper Junos Os Evolved, published on 8 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in Juniper Networks Junos OS Evolved may allow an attacker to cause a Denial of Service (DoS) by sending a high rate of specific packets to the device, resulting in a pfemand process crash. The pfemand process is responsible for packet forwarding on the device. By continuously sending the packet flood, an attacker can repeatedly crash the pfemand process causing a sustained Denial of Service. This issue can only be triggered by traffic sent to the device. Transit traffic does not cause this issue. This issue affects all version of Junos OS Evolved prior to 19.1R1-EVO.

## Which versions are affected by CVE-2020-1626?

It affects 1 product.


Products: Juniper Junos Os Evolved.

## How do I fix CVE-2020-1626?

No fix has been published for CVE-2020-1626 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-1626 being exploited?

There is no known exploitation of CVE-2020-1626 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-2020-1626 and fix it if it is affected.

What it is: CVE-2020-1626 is a high-severity denial of service vulnerability in Juniper Junos Os Evolved, 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-2020-1626 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-2020-1626/ (Markdown: https://insights.sbomify.com/CVE-2020-1626/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1626
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1626
- OSV: https://osv.dev/vulnerability/CVE-2020-1626

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-1626/
Summaries are generated and may contain mistakes; the official description above is the record.