# CVE-2021-28510: Denial of service in EOS

> An attacker can cause a denial of service on Arista EOS devices by sending malformed PTP packets that trigger repeated PTP agent restarts.

- **Severity:** Medium 5.3 (`CVSS:3.1/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 Jan 2023
- **Updated:** 1 Apr 2025
- **Also known as:** GHSA-c5c5-rwc6-67m5

## What is CVE-2021-28510?

CVE-2021-28510 is a medium-severity denial of service vulnerability in Arista Networks EOS, published on 24 Jan 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

For certain systems running EOS, a Precision Time Protocol (PTP) packet of a management/signaling message with an invalid Type-Length-Value (TLV) causes the PTP agent to restart. Repeated restarts of the service will make the service unavailable.

Weakness: CWE-1284 (Improper Validation of Specified Quantity in Input), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2021-28510?

It affects 1 product.


Products: Arista Eos.

## How do I fix CVE-2021-28510?

No fix has been published for CVE-2021-28510 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-28510 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-28510 exists.

## Other vulnerabilities in Arista Networks EOS

- [CVE-2026-7473](https://insights.sbomify.com/CVE-2026-7473/): Arista Extensible Operating System Incomplete Comparison with Missing Factors (medium 6.9, exploited in the wild)
- [CVE-2015-8236](https://insights.sbomify.com/CVE-2015-8236/): Privilege escalation in n/a (critical 10.0)
- [CVE-2020-10188](https://insights.sbomify.com/CVE-2020-10188/): Memory corruption in n/a (critical 9.8)
- [CVE-2017-18017](https://insights.sbomify.com/CVE-2017-18017/): Use after free in n/a (critical 9.8)
- [CVE-2017-14491](https://insights.sbomify.com/CVE-2017-14491/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28510 and fix it if it is affected.

What it is: CVE-2021-28510 is a medium-severity denial of service vulnerability in Arista Networks EOS, published on 24 Jan 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-28510 exists.

Affected product: Arista Networks EOS. 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-2021-28510/ (Markdown: https://insights.sbomify.com/CVE-2021-28510/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28510
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28510
- OSV: https://osv.dev/vulnerability/CVE-2021-28510

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28510/
Summaries are generated and may contain mistakes; the official description above is the record.