# CVE-2017-6666: Denial of service in Cisco Network Convergence System 5500 Series Routers

> An authenticated local attacker can cause a denial of service by stopping traffic forwarding on Cisco NCS 5500 routers.

- **Severity:** Medium 6.0 (`CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 13 Jun 2017
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-f277-hhxj-fvx5

## What is CVE-2017-6666?

CVE-2017-6666 is a medium-severity denial of service vulnerability in Cisco Ios Xr, published on 13 Jun 2017. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in the forwarding component of Cisco IOS XR Software for Cisco Network Convergence System (NCS) 5500 Series Routers could allow an authenticated, local attacker to cause the router to stop forwarding data traffic across Traffic Engineering (TE) tunnels, resulting in a denial of service (DoS) condition. More Information: CSCvd16665. Known Affected Releases: 6.2.11.BASE. Known Fixed Releases: 6.1.3 6.1.2 6.3.1.8i.BASE 6.2.11.8i.BASE 6.2.2.9i.BASE 6.1.32.11i.BASE 6.1.31.10i.BASE 6.1.4.3i.BASE.

## Which versions are affected by CVE-2017-6666?

It affects 1 product.


Products: Cisco Ios Xr.

## How do I fix CVE-2017-6666?

No fix has been published for CVE-2017-6666 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-6666 being exploited?

There is no known exploitation of CVE-2017-6666 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Ios Xr

- [CVE-2020-3118](https://insights.sbomify.com/CVE-2020-3118/): Cisco IOS XR Software Discovery Protocol Format String (high 8.8, exploited in the wild)
- [CVE-2020-3569](https://insights.sbomify.com/CVE-2020-3569/): Cisco IOS XR Software DVMRP Memory Exhaustion (high 8.6, exploited in the wild)
- [CVE-2020-3566](https://insights.sbomify.com/CVE-2020-3566/): Cisco IOS XR Software DVMRP Memory Exhaustion (high 8.6, exploited in the wild)
- [CVE-2010-3035](https://insights.sbomify.com/CVE-2010-3035/): Cisco IOS XR Border Gateway Protocol (BGP) Denial-of-Service (high 7.5, exploited in the wild)
- [CVE-2022-20821](https://insights.sbomify.com/CVE-2022-20821/): Cisco IOS XR Open Port (medium 6.5, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-6666 and fix it if it is affected.

What it is: CVE-2017-6666 is a medium-severity denial of service vulnerability in Cisco Ios Xr, published on 13 Jun 2017. 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-2017-6666 in the wild and no public exploit code.

Affected product: Cisco Ios Xr. 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-2017-6666/ (Markdown: https://insights.sbomify.com/CVE-2017-6666/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-6666
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-6666
- OSV: https://osv.dev/vulnerability/CVE-2017-6666

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From sbomify Insights: https://insights.sbomify.com/CVE-2017-6666/
Summaries are generated and may contain mistakes; the official description above is the record.