# CVE-2021-39725: Use after free in Android

> A double free vulnerability in the Android kernel allows local attackers with system privileges to escalate privileges.

- **Severity:** Medium 6.7 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Mar 2022
- **Updated:** 4 Aug 2024
- **Also known as:** A-151454974, GHSA-hgxv-8gp2-j88j, PUB-A-151454974

## What is CVE-2021-39725?

CVE-2021-39725 is a medium-severity use after free vulnerability in Google Android, published on 16 Mar 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In gasket_free_coherent_memory_all of gasket_page_table.c, there is a possible memory corruption due to a double free. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-151454974References: N/A

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2021-39725?

It affects 1 product.


Products: Google Android.

## How do I fix CVE-2021-39725?

Apply the vendor's patch.

## Is CVE-2021-39725 being exploited?

There is no known exploitation of CVE-2021-39725 in the wild and no public exploit code.

## Other vulnerabilities in Google Android

- [CVE-2026-58704](https://insights.sbomify.com/CVE-2026-58704/): Google Pixel Improper Authorization (high 8.8, exploited in the wild)
- [CVE-2025-48543](https://insights.sbomify.com/CVE-2025-48543/): Android Runtime Use-After-Free (high 8.8, exploited in the wild)
- [CVE-2023-35674](https://insights.sbomify.com/CVE-2023-35674/): Android Framework Privilege Escalation (high 8.8, exploited in the wild)
- [CVE-2025-48595](https://insights.sbomify.com/CVE-2025-48595/): Android Framework Integer Overflow (high 8.4, exploited in the wild)
- [CVE-2024-32896](https://insights.sbomify.com/CVE-2024-32896/): Android Pixel Privilege Escalation (high 8.1, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-39725 and fix it if it is affected.

What it is: CVE-2021-39725 is a medium-severity use after free vulnerability in Google Android, published on 16 Mar 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-2021-39725 in the wild and no public exploit code.

Affected product: Google Android. 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-2021-39725/ (Markdown: https://insights.sbomify.com/CVE-2021-39725/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-39725
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-39725
- OSV: https://osv.dev/vulnerability/CVE-2021-39725

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-39725/
Summaries are generated and may contain mistakes; the official description above is the record.