# CVE-2017-2340: Denial of service in Junos OS on M/MX platforms where Enhanced Subscriber Management for DHCPv6 subscribers is configured

> Attackers can cause a Packet Forwarding Engine crash on Juniper M/MX routers by sending crafted IPv6 ND packets when Enhanced Subscriber Management is enabled.

- **Severity:** Medium 5.3 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Apr 2017
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-52f2-j43x-hh76

## What is CVE-2017-2340?

CVE-2017-2340 is a medium-severity denial of service vulnerability in Juniper Junos, published on 24 Apr 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

On Juniper Networks Junos OS 15.1 releases from 15.1R3 to 15.1R4, 16.1 prior to 16.1R3, on M/MX platforms where Enhanced Subscriber Management for DHCPv6 subscribers is configured, a vulnerability in processing IPv6 ND packets originating from subscribers and destined to M/MX series routers can result in a PFE (Packet Forwarding Engine) hang or crash.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2017-2340?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2017-2340?

No fix has been published for CVE-2017-2340 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-2340 being exploited?

There is no known exploitation of CVE-2017-2340 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-2017-2340 and fix it if it is affected.

What it is: CVE-2017-2340 is a medium-severity denial of service vulnerability in Juniper Junos, published on 24 Apr 2017. 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-2017-2340 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-2017-2340/ (Markdown: https://insights.sbomify.com/CVE-2017-2340/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-2340
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-2340
- OSV: https://osv.dev/vulnerability/CVE-2017-2340

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-2340/
Summaries are generated and may contain mistakes; the official description above is the record.