# CVE-2021-28663: Arm Mali Graphics Processing Unit (GPU) Use-After-Free

> Attackers can exploit a use-after-free in the Arm Mali GPU kernel driver to escalate privileges or disclose information on Android devices.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 3 Nov 2021 (CISA KEV)
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 May 2021
- **Updated:** 21 Oct 2025
- **Also known as:** A-174259860, ASB-A-174259860, GHSA-2rc2-892p-6hc2

## What is CVE-2021-28663?

CVE-2021-28663 is a high-severity use after free vulnerability in Arm Valhall Gpu Kernel Driver, published on 10 May 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

The Arm Mali GPU kernel driver allows privilege escalation or information disclosure because GPU memory operations are mishandled, leading to a use-after-free. This affects Bifrost r0p0 through r28p0 before r29p0, Valhall r19p0 through r28p0 before r29p0, and Midgard r4p0 through r30p0.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2021-28663?

It affects 3 products.


Products: Arm Bifrost Gpu Kernel Driver, Arm Midgard Gpu Kernel Driver, Arm Valhall Gpu Kernel Driver.

## How do I fix CVE-2021-28663?

Apply the vendor's patch. US federal agencies must fix it by 17 Nov 2021.

## Is CVE-2021-28663 being exploited?

Yes. Attackers have exploited CVE-2021-28663 in the wild since at least 3 Nov 2021.

Public exploit code:

- A basic PoC leak for CVE-2021-28663 (Internal of the Android kernel backdoor vulnerability) (github_poc): https://github.com/lntrx/CVE-2021-28663

## Other vulnerabilities in Arm Valhall Gpu Kernel Driver

- [CVE-2022-38181](https://insights.sbomify.com/CVE-2022-38181/): Arm Mali GPU Kernel Driver Use-After-Free (high 8.8, exploited in the wild)
- [CVE-2021-29256](https://insights.sbomify.com/CVE-2021-29256/): Arm Mali GPU Kernel Driver Use-After-Free (high 8.8, exploited in the wild)
- [CVE-2021-28664](https://insights.sbomify.com/CVE-2021-28664/): Arm Mali Graphics Processing Unit (GPU) Unspecified (high 8.8, exploited in the wild)
- [CVE-2022-22706](https://insights.sbomify.com/CVE-2022-22706/): Arm Mali GPU Kernel Driver Unspecified (high 7.8, exploited in the wild)
- [CVE-2024-4610](https://insights.sbomify.com/CVE-2024-4610/): Arm Mali GPU Kernel Driver Use-After-Free (high 7.4, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28663 and fix it if it is affected.

What it is: CVE-2021-28663 is a high-severity use after free vulnerability in Arm Valhall Gpu Kernel Driver, published on 10 May 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2021-28663 in the wild since at least 3 Nov 2021.

Affected product: Arm Valhall Gpu Kernel Driver. 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-2021-28663/ (Markdown: https://insights.sbomify.com/CVE-2021-28663/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28663
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28663
- OSV: https://osv.dev/vulnerability/CVE-2021-28663

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-28663/
Summaries are generated and may contain mistakes; the official description above is the record.