# CVE-2023-44186: Denial of service in Junos OS

> Attackers can crash Junos OS routers by sending crafted BGP updates with long AS paths when Non-Stop Routing is enabled.

- **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:** 11 Oct 2023
- **Updated:** 3 Dec 2024
- **Also known as:** GHSA-8pvv-px4f-4px7

## What is CVE-2023-44186?

CVE-2023-44186 is a high-severity denial of service vulnerability in Juniper Junos, published on 11 Oct 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An Improper Handling of Exceptional Conditions vulnerability in AS PATH processing of Juniper Networks Junos OS and Junos OS Evolved allows an attacker to send a BGP update message with an AS PATH containing a large number of 4-byte ASes, leading to a Denial of Service (DoS). Continued receipt and processing of these BGP updates will create a sustained Denial of Service (DoS) condition.

This issue is hit when the router has Non-Stop Routing (NSR) enabled, has a non-4-byte-AS capable BGP neighbor, receives a BGP update message with a prefix that includes a long AS PATH containing large number of 4-byte ASes, and has to advertise the prefix towards the non-4-byte-AS capable BGP neighbor.

Note: NSR is not supported on the SRX Series and is therefore not affected by this vulnerability.
This issue affects:

Juniper Networks Junos OS:

  *  All versions prior to 20.4R3-S8;
  *  21.1 versions 21.1R1 and later;
  *  21.2 versions prior to 21.2R3-S6;
  *  21.3 versions prior to 21.3R3-S5;
  *  21.4 versions prior to 21.4R3-S5;
  *  22.1 versions prior to 22.1R3-S4;
  *  22.2 versions prior to 22.2R3-S2;
  *  22.3 versions prior to 22.3R2-S2, 22.3R3-S1;
  *  22.4 versions prior to 22.4R2-S1, 22.4R3.

Juniper Networks Junos OS Evolved

  *  All versions prior to 20.4R3-S8-EVO;
  *  21.1 versions 21.1R1-EVO and later;
  *  21.2 versions prior to 21.2R3-S6-EVO;
  *  21.3 versions prior to 21.3R3-S5-EVO;
  *  21.4 versions prior to 21.4R3-S5-EVO;
  *  22.1 versions prior to 22.1R3-S4-EVO;
  *  22.2 versions prior to 22.2R3-S2-EVO;
  *  22.3 versions prior to 22.3R2-S2-EVO, 22.3R3-S1-EVO;
  *  22.4 versions prior to 22.4R2-S1-EVO, 22.4R3-EVO.

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

## Which versions are affected by CVE-2023-44186?

It affects 2 products.


Products: Juniper Junos, Juniper Junos Os Evolved.

## How do I fix CVE-2023-44186?

No fix has been published for CVE-2023-44186 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-44186 being exploited?

There is no known exploitation of CVE-2023-44186 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-2023-44186 and fix it if it is affected.

What it is: CVE-2023-44186 is a high-severity denial of service vulnerability in Juniper Junos, published on 11 Oct 2023. 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-2023-44186 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-2023-44186/ (Markdown: https://insights.sbomify.com/CVE-2023-44186/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-44186
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-44186
- OSV: https://osv.dev/vulnerability/CVE-2023-44186

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-44186/
Summaries are generated and may contain mistakes; the official description above is the record.