# CVE-2026-20433: Memory corruption in MediaTek chipset

> A missing bounds check in MediaTek modem firmware allows remote privilege escalation via a rogue base station, requiring user interaction.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/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:** Yes
- **Published:** 7 Apr 2026
- **Updated:** 8 Apr 2026
- **Also known as:** A-480745371, ASB-A-480745371, GHSA-5h6h-2wjp-jc72, M-MOLY01088681

## What is CVE-2026-20433?

CVE-2026-20433 is a high-severity memory corruption vulnerability in MediaTek, Inc. MediaTek chipset, published on 7 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In Modem, there is a possible out of bounds write due to a missing bounds check. This could lead to remote escalation of privilege, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is needed for exploitation. Patch ID: MOLY01088681; Issue ID: MSV-4460.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-20433?

It affects 62 products.


Products: Mediatek Mt2735 Firmware, Mediatek Mt2737 Firmware, Mediatek Mt6813 Firmware, Mediatek Mt6833 Firmware, Mediatek Mt6833p Firmware, Mediatek Mt6835 Firmware, Mediatek Mt6835t Firmware, Mediatek Mt6853 Firmware, Mediatek Mt6853t Firmware, Mediatek Mt6855 Firmware, Mediatek Mt6855t Firmware, Mediatek Mt6873 Firmware, Mediatek Mt6875 Firmware, Mediatek Mt6875t Firmware, Mediatek Mt6877 Firmware, Mediatek Mt6877t Firmware, Mediatek Mt6877tt Firmware, Mediatek Mt6878 Firmware, Mediatek Mt6878m Firmware, Mediatek Mt6879 Firmware and 42 more.

## How do I fix CVE-2026-20433?

Apply the vendor's patch.

## Is CVE-2026-20433 being exploited?

There is no known exploitation of CVE-2026-20433 in the wild and no public exploit code.

## Other vulnerabilities in MediaTek, Inc. MediaTek chipset

- [CVE-2026-20432](https://insights.sbomify.com/CVE-2026-20432/): Memory corruption in MediaTek chipset (high 8.0)
- [CVE-2026-20479](https://insights.sbomify.com/CVE-2026-20479/): Denial of service in MediaTek chipset (high 7.5)
- [CVE-2026-20528](https://insights.sbomify.com/CVE-2026-20528/): Memory corruption in MediaTek chipset (medium 6.7)
- [CVE-2026-20449](https://insights.sbomify.com/CVE-2026-20449/): Memory corruption in MediaTek chipset (medium 6.5)
- [CVE-2026-20450](https://insights.sbomify.com/CVE-2026-20450/): Denial of service in MediaTek chipset (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-20433 and fix it if it is affected.

What it is: CVE-2026-20433 is a high-severity memory corruption vulnerability in MediaTek, Inc. MediaTek chipset, published on 7 Apr 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-2026-20433 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-2026-20433/ (Markdown: https://insights.sbomify.com/CVE-2026-20433/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-20433
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20433
- OSV: https://osv.dev/vulnerability/CVE-2026-20433

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-20433/
Summaries are generated and may contain mistakes; the official description above is the record.