# CVE-2020-1643: Denial of service in Junos OS

> A local attacker can crash the routing process on specific Juniper EX switches by repeatedly executing CLI commands when OSPF authentication is enabled.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 17 Jul 2020
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-9fv5-j7w3-ph59

## What is CVE-2020-1643?

CVE-2020-1643 is a medium-severity denial of service vulnerability in Juniper Junos, published on 17 Jul 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Execution of the "show ospf interface extensive" or "show ospf interface detail" CLI commands on a Juniper Networks device running Junos OS may cause the routing protocols process (RPD) to crash and restart if OSPF interface authentication is configured, leading to a Denial of Service (DoS). By continuously executing the same CLI commands, a local attacker can repeatedly crash the RPD process causing a sustained Denial of Service. Note: Only systems utilizing ARM processors, found on the EX2300 and EX3400, are vulnerable to this issue. Systems shipped with other processor architectures are not vulnerable to this issue. The processor architecture can be displayed via the 'uname -a' command. For example: ARM (vulnerable): % uname -a | awk '{print $NF}' arm PowerPC (not vulnerable): % uname -a | awk '{print $NF}' powerpc AMD (not vulnerable): % uname -a | awk '{print $NF}' amd64 Intel (not vulnerable): % uname -a | awk '{print $NF}' i386 This issue affects Juniper Networks Junos OS: 12.3X48 versions prior to 12.3X48-D100; 14.1X53 versions prior to 14.1X53-D140, 14.1X53-D54; 15.1 versions prior to 15.1R7-S7; 15.1X49 versions prior to 15.1X49-D210; 15.1X53 versions prior to 15.1X53-D593; 16.1 versions prior to 16.1R7-S8; 17.1 versions prior to 17.1R2-S12; 17.2 versions prior to 17.2R3-S4; 17.3 versions prior to 17.3R3-S8; 17.4 versions prior to 17.4R2-S2, 17.4R3; 18.1 versions prior to 18.1R3-S2; 18.2 versions prior to 18.2R2, 18.2R3; 18.2X75 versions prior to 18.2X75-D40; 18.3 versions prior to 18.3R1-S2, 18.3R2.

Weakness: CWE-755 (Improper Handling of Exceptional Conditions)

## Which versions are affected by CVE-2020-1643?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2020-1643?

No fix has been published for CVE-2020-1643 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-1643 being exploited?

There is no known exploitation of CVE-2020-1643 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-2020-1643 and fix it if it is affected.

What it is: CVE-2020-1643 is a medium-severity denial of service vulnerability in Juniper Junos, published on 17 Jul 2020. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-1643 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-2020-1643/ (Markdown: https://insights.sbomify.com/CVE-2020-1643/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1643
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1643
- OSV: https://osv.dev/vulnerability/CVE-2020-1643

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-1643/
Summaries are generated and may contain mistakes; the official description above is the record.