# CVE-2021-1353: Cisco StarOS IPv4 Denial of Service Vulnerability

> Remote unauthenticated attackers can cause a denial of service on Cisco StarOS devices by sending crafted IPv4 packets that trigger a memory leak.

- **Severity:** Medium 5.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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:** 20 Jan 2021
- **Updated:** 12 Nov 2024
- **Also known as:** GHSA-92xw-vwgc-8994

## What is CVE-2021-1353?

CVE-2021-1353 is a medium-severity denial of service vulnerability in Cisco ASR 5000 Series Software, published on 20 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the IPv4 protocol handling of Cisco StarOS could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a memory leak that occurs during packet processing. An attacker could exploit this vulnerability by sending a series of crafted IPv4 packets through an affected device. A successful exploit could allow the attacker to exhaust the available memory and cause an unexpected restart of the npusim process, leading to a DoS condition on the affected device.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2021-1353?

It affects 2 products.


Products: Cisco Staros, Cisco Virtualized Packet Core-Single Instance.

## How do I fix CVE-2021-1353?

No fix has been published for CVE-2021-1353 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-1353 being exploited?

There is no known exploitation of CVE-2021-1353 in the wild and no public exploit code.

## Other vulnerabilities in Cisco ASR 5000 Series Software

- [CVE-2023-20046](https://insights.sbomify.com/CVE-2023-20046/): Auth bypass in Cisco ASR 5000 Series Software (high 8.8)
- [CVE-2019-1869](https://insights.sbomify.com/CVE-2019-1869/): Cisco StarOS Denial of Service Vulnerability (high 8.6)
- [CVE-2018-0369](https://insights.sbomify.com/CVE-2018-0369/): Denial of service in Cisco StarOS unknown (high 8.6)
- [CVE-2017-6707](https://insights.sbomify.com/CVE-2017-6707/): Command injection in Cisco StarOS (high 8.2)
- [CVE-2021-1539](https://insights.sbomify.com/CVE-2021-1539/): Cisco ASR 5000 Series Software Authorization Bypass Vulnerabilities (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-1353 and fix it if it is affected.

What it is: CVE-2021-1353 is a medium-severity denial of service vulnerability in Cisco ASR 5000 Series Software, published on 20 Jan 2021. 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-2021-1353 in the wild and no public exploit code.

Affected product: Cisco ASR 5000 Series Software. 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-2021-1353/ (Markdown: https://insights.sbomify.com/CVE-2021-1353/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-1353
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1353
- OSV: https://osv.dev/vulnerability/CVE-2021-1353

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-1353/
Summaries are generated and may contain mistakes; the official description above is the record.