# CVE-2026-20521: Memory corruption in MediaTek chipset

> A missing bounds check in the Video HAL allows local attackers to escalate privileges without user interaction or additional execution rights.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Oct 2026
- **Updated:** 6 Oct 2026
- **Also known as:** GHSA-qpf3-2wfg-8hrm

## What is CVE-2026-20521?

CVE-2026-20521 is a high-severity memory corruption vulnerability in MediaTek, Inc. MediaTek chipset, published on 5 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In Video HAL, there is a possible escalation of privilege due to a missing bounds check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: ALPS11375674; Issue ID: MSV-9571.

Weakness: CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-20521?

It affects 48 products.


Products: Mediatek Mt2718 Firmware, Mediatek Mt6768 Firmware, Mediatek Mt6769 Firmware, Mediatek Mt6781 Firmware, Mediatek Mt6789 Firmware, Mediatek Mt6833 Firmware, Mediatek Mt6835 Firmware, Mediatek Mt6853 Firmware, Mediatek Mt6855 Firmware, Mediatek Mt6858 Firmware, Mediatek Mt6877 Firmware, Mediatek Mt6878 Firmware, Mediatek Mt6879 Firmware, Mediatek Mt6881 Firmware, Mediatek Mt6883 Firmware, Mediatek Mt6885 Firmware, Mediatek Mt6886 Firmware, Mediatek Mt6889 Firmware, Mediatek Mt6893 Firmware, Mediatek Mt6895 Firmware and 28 more.

## How do I fix CVE-2026-20521?

No fix has been published for CVE-2026-20521 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-20521 being exploited?

There is no known exploitation of CVE-2026-20521 in the wild and no public exploit code.

## Other vulnerabilities in MediaTek, Inc. MediaTek chipset

- [CVE-2026-20586](https://insights.sbomify.com/CVE-2026-20586/): Memory corruption in MediaTek chipset (high 8.8)
- [CVE-2026-20501](https://insights.sbomify.com/CVE-2026-20501/): Memory corruption in MediaTek chipset (high 8.4)
- [CVE-2026-20502](https://insights.sbomify.com/CVE-2026-20502/): Memory corruption in MediaTek chipset (high 8.4)
- [CVE-2026-20530](https://insights.sbomify.com/CVE-2026-20530/): Memory corruption in MediaTek chipset (medium 6.7)
- [CVE-2026-20542](https://insights.sbomify.com/CVE-2026-20542/): Use after free in MediaTek chipset (medium 6.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-20521 and fix it if it is affected.

What it is: CVE-2026-20521 is a high-severity memory corruption vulnerability in MediaTek, Inc. MediaTek chipset, published on 5 Oct 2026. 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-2026-20521 in the wild and no public exploit code.

Affected product: MediaTek, Inc. MediaTek chipset. 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-2026-20521/ (Markdown: https://insights.sbomify.com/CVE-2026-20521/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-20521
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20521
- OSV: https://osv.dev/vulnerability/CVE-2026-20521

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-20521/
Summaries are generated and may contain mistakes; the official description above is the record.