# CVE-2019-0056: Denial of service in Junos OS

> An attacker can cause a Denial of Service on Juniper MX routers by flooding specific IPv6 packets, disrupting OSPF routing and traffic forwarding.

- **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:** 9 Oct 2019
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-mjmc-mxc5-2f3v

## What is CVE-2019-0056?

CVE-2019-0056 is a high-severity denial of service vulnerability in Juniper Junos, published on 9 Oct 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

This issue only affects devices with three (3) or more MPC10's installed in a single chassis with OSPF enabled and configured on the device. An Insufficient Resource Pool weakness allows an attacker to cause the device's Open Shortest Path First (OSPF) states to transition to Down, resulting in a Denial of Service (DoS) attack. This attack requires a relatively large number of specific Internet Mixed (IMIXed) types of genuine and valid IPv6 packets to be transferred by the attacker in a relatively short period of time, across three or more PFE's on the device at the same time. Continued receipt of the traffic sent by the attacker will continue to cause OSPF to remain in the Down starting state, or flap between other states and then again to Down, causing a persistent Denial of Service. This attack will affect all IPv4, and IPv6 traffic served by the OSPF routes once the OSPF states transition to Down. This issue affects: Juniper Networks Junos OS on MX480, MX960, MX2008, MX2010, MX2020: 18.1 versions prior to 18.1R2-S4, 18.1R3-S5; 18.1X75 version 18.1X75-D10 and later versions; 18.2 versions prior to 18.2R1-S5, 18.2R2-S3, 18.2R3; 18.2X75 versions prior to 18.2X75-D50; 18.3 versions prior to 18.3R1-S4, 18.3R2, 18.3R3; 18.4 versions prior to 18.4R1-S2, 18.4R2.

Weakness: CWE-410 (Insufficient Resource Pool)

## Which versions are affected by CVE-2019-0056?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2019-0056?

No fix has been published for CVE-2019-0056 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-0056 being exploited?

There is no known exploitation of CVE-2019-0056 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-2019-0056 and fix it if it is affected.

What it is: CVE-2019-0056 is a high-severity denial of service vulnerability in Juniper Junos, published on 9 Oct 2019. 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-2019-0056 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-2019-0056/ (Markdown: https://insights.sbomify.com/CVE-2019-0056/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-0056
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-0056
- OSV: https://osv.dev/vulnerability/CVE-2019-0056

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-0056/
Summaries are generated and may contain mistakes; the official description above is the record.