# CVE-2016-6455: Denial of service in Cisco StarOS 18.x through 21.x

> An unauthenticated remote attacker can disconnect subscriber sessions on Cisco ASR 5500 routers, causing a partial denial of service.

- **Severity:** High 7.5 (`CVSS:3.0/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:** 3 Nov 2016
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-c5xh-8h52-w9w3

## What is CVE-2016-6455?

CVE-2016-6455 is a high-severity denial of service vulnerability in Cisco StarOS 18.x through 21.x, published on 3 Nov 2016. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the Slowpath of StarOS for Cisco ASR 5500 Series routers with Data Processing Card 2 (DPC2) could allow an unauthenticated, remote attacker to cause a subset of the subscriber sessions to be disconnected, resulting in a partial denial of service (DoS) condition. This vulnerability affects Cisco ASR 5500 devices with Data Processing Card 2 (DPC2) running StarOS 18.0 or later. More Information: CSCvb12081. Known Affected Releases: 18.7.4 19.5.0 20.0.2.64048 20.2.3 21.0.0. Known Fixed Releases: 18.7.4 18.7.4.65030 18.8.M0.65044 19.5.0 19.5.0.65092 19.5.M0.65023 19.5.M0.65050 20.2.3 20.2.3.64982 20.2.3.65017 20.2.a4.65307 20.3.M0.64984 20.3.M0.65029 20.3.M0.65037 20.3.M0.65071 20.3.T0.64985 20.3.T0.65031 20.3.T0.65043 20.3.T0.65067 21.0.0 21.0.0.65256 21.0.M0.64922 21.0.M0.64983 21.0.M0.65140 21.0.V0.65150 21.1.A0.64932 21.1.A0.64987 21.1.A0.65145 21.1.PP0.65270 21.1.R0.65130 21.1.R0.65135 21.1.R0.65154 21.1.VC0.65203 21.2.A0.65147.

Weakness: CWE-399

## Which versions are affected by CVE-2016-6455?

It affects 1 product.


Products: Cisco Asr 5000 Software.

## How do I fix CVE-2016-6455?

No fix has been published for CVE-2016-6455 yet. Limit exposure of the affected software until one is available.

## Is CVE-2016-6455 being exploited?

There is no known exploitation of CVE-2016-6455 in the wild and no public exploit code.

## Other vulnerabilities in Cisco StarOS 18.x through 21.x

- [CVE-2017-6729](https://insights.sbomify.com/CVE-2017-6729/): Denial of service in Cisco StarOS (high 7.5)
- [CVE-2016-1436](https://insights.sbomify.com/CVE-2016-1436/): Denial of service in n/a (high 7.5)
- [CVE-2017-6773](https://insights.sbomify.com/CVE-2017-6773/): Command injection in StarOS for ASR 5000 Series Aggregated Services Routers (medium 6.7)
- [CVE-2017-6775](https://insights.sbomify.com/CVE-2017-6775/): Privilege escalation in StarOS for ASR 5000 Series Aggregated Services Routers (medium 5.7)
- [CVE-2017-6774](https://insights.sbomify.com/CVE-2017-6774/): Path traversal in StarOS for ASR 5000 Series Aggregated Services Routers (medium 5.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-6455 and fix it if it is affected.

What it is: CVE-2016-6455 is a high-severity denial of service vulnerability in Cisco StarOS 18.x through 21.x, published on 3 Nov 2016. 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-2016-6455 in the wild and no public exploit code.

Affected product: Cisco StarOS 18.x through 21.x. 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-2016-6455/ (Markdown: https://insights.sbomify.com/CVE-2016-6455/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-6455
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-6455
- OSV: https://osv.dev/vulnerability/CVE-2016-6455

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-6455/
Summaries are generated and may contain mistakes; the official description above is the record.