# CVE-2021-28714: Denial of service in Linux

> A malicious guest can exhaust host kernel memory by bypassing netback driver limits, causing denial of service on the host system.

- **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:** 6 Jan 2022
- **Updated:** 3 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-28714, GHSA-3f3x-x2x3-wvhg, UBUNTU-CVE-2021-28714

## What is CVE-2021-28714?

CVE-2021-28714 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 6 Jan 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Guest can force Linux netback driver to hog large amounts of kernel memory T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] Incoming data packets for a guest in the Linux kernel's netback driver are buffered until the guest is ready to process them. There are some measures taken for avoiding to pile up too much data, but those can be bypassed by the guest: There is a timeout how long the client side of an interface can stop consuming new packets before it is assumed to have stalled, but this timeout is rather long (60 seconds by default). Using a UDP connection on a fast interface can easily accumulate gigabytes of data in that time. (CVE-2021-28715) The timeout could even never trigger if the guest manages to have only one free slot in its RX queue ring page and the next package would require more than one free slot, which may be the case when using GSO, XDP, or software hashing. (CVE-2021-28714)

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2021-28714?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2021-28714?

Apply the vendor's patch.

## Is CVE-2021-28714 being exploited?

There is no known exploitation of CVE-2021-28714 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-2021-28714 and fix it if it is affected.

What it is: CVE-2021-28714 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 6 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-2021-28714 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-2021-28714/ (Markdown: https://insights.sbomify.com/CVE-2021-28714/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28714
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28714
- OSV: https://osv.dev/vulnerability/CVE-2021-28714

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28714/
Summaries are generated and may contain mistakes; the official description above is the record.