# CVE-2018-0063: Denial of service in Junos OS

> An attacker can cause a sustained denial of service on the management interface by flooding ARP requests, exhausting the next-hop index database.

- **Severity:** Medium 6.5 (`CVSS:3.0/AV:A/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Oct 2018
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-q5f4-25c6-4r45

## What is CVE-2018-0063?

CVE-2018-0063 is a medium-severity denial of service vulnerability in Juniper Junos, published on 10 Oct 2018. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in the IP next-hop index database in Junos OS 17.3R3 may allow a flood of ARP requests, sent to the management interface, to exhaust the private Internal routing interfaces (IRIs) next-hop limit. Once the IRI next-hop database is full, no further next hops can be learned and existing entries cannot be cleared, leading to a sustained denial of service (DoS) condition. An indicator of compromise for this issue is the report of the following error message: %KERN-4: Nexthop index allocation failed: private index space exhausted This issue only affects the management interface, and does not impact regular transit traffic through the FPCs. This issue also only affects Junos OS 17.3R3. No prior versions of Junos OS are affected by this issue. Affected releases are Juniper Networks Junos OS: 17.3R3.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2018-0063?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2018-0063?

No fix has been published for CVE-2018-0063 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-0063 being exploited?

There is no known exploitation of CVE-2018-0063 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-2018-0063 and fix it if it is affected.

What it is: CVE-2018-0063 is a medium-severity denial of service vulnerability in Juniper Junos, published on 10 Oct 2018. 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-2018-0063 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-2018-0063/ (Markdown: https://insights.sbomify.com/CVE-2018-0063/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-0063
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-0063
- OSV: https://osv.dev/vulnerability/CVE-2018-0063

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-0063/
Summaries are generated and may contain mistakes; the official description above is the record.