# CVE-2020-0421: Memory corruption in Android

> A local attacker can escalate privileges via an out-of-bounds write in Android's String8.cpp without user interaction.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 14 Oct 2020
- **Updated:** 4 Aug 2024
- **Also known as:** A-161894517, ASB-A-161894517, GHSA-29fp-7w52-3694

## What is CVE-2020-0421?

CVE-2020-0421 is a high-severity memory corruption vulnerability in Google Android, published on 14 Oct 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In appendFormatV of String8.cpp, there is a possible out of bounds write due to incorrect error handling. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-8.1 Android-9 Android-10 Android-11 Android-8.0Android ID: A-161894517

Weakness: CWE-787 (Out-of-bounds Write), CWE-755 (Improper Handling of Exceptional Conditions)

## Which versions are affected by CVE-2020-0421?

It affects 1 product.


Products: Google Android.

## How do I fix CVE-2020-0421?

Apply the vendor's patch.

## Is CVE-2020-0421 being exploited?

There is no known exploitation of CVE-2020-0421 in the wild and no public exploit code.

Public exploit code:

- https://github.com/nanopathi/system_core_AOSP10_r33_CVE-2020-0421 (github_poc): https://github.com/nanopathi/system_core_AOSP10_r33_CVE-2020-0421

## 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-2020-0421 and fix it if it is affected.

What it is: CVE-2020-0421 is a high-severity memory corruption vulnerability in Google Android, published on 14 Oct 2020. 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-2020-0421 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-2020-0421/ (Markdown: https://insights.sbomify.com/CVE-2020-0421/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-0421
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-0421
- OSV: https://osv.dev/vulnerability/CVE-2020-0421

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-0421/
Summaries are generated and may contain mistakes; the official description above is the record.