# CVE-2021-28713: Denial of service in Linux

> A malicious driver domain can cause denial of service in guest VMs by sending high-frequency console events, requiring patched Xen hypervisors.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 Jan 2022
- **Updated:** 3 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-28713, GHSA-5qm6-7cgc-v552, UBUNTU-CVE-2021-28713

## What is CVE-2021-28713?

CVE-2021-28713 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 5 Jan 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Rogue backends can cause DoS of guests via high frequency events T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] Xen offers the ability to run PV backends in regular unprivileged guests, typically referred to as "driver domains". Running PV backends in driver domains has one primary security advantage: if a driver domain gets compromised, it doesn't have the privileges to take over the system. However, a malicious driver domain could try to attack other guests via sending events at a high frequency leading to a Denial of Service in the guest due to trying to service interrupts for elongated amounts of time. There are three affected backends: * blkfront patch 1, CVE-2021-28711 * netfront patch 2, CVE-2021-28712 * hvc_xen (console) patch 3, CVE-2021-28713

## Which versions are affected by CVE-2021-28713?

It affects 2 products.


Products: Debian Debian Linux, Xen Xen.

## How do I fix CVE-2021-28713?

Apply the vendor's patch.

## Is CVE-2021-28713 being exploited?

There is no known exploitation of CVE-2021-28713 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28713 and fix it if it is affected.

What it is: CVE-2021-28713 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 5 Jan 2022. 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-2021-28713 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2021-28713/ (Markdown: https://insights.sbomify.com/CVE-2021-28713/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28713
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28713
- OSV: https://osv.dev/vulnerability/CVE-2021-28713

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28713/
Summaries are generated and may contain mistakes; the official description above is the record.