# CVE-2026-20479: Denial of service in MediaTek chipset

> A missing bounds check in MediaTek modem firmware allows remote attackers to cause denial of service via a rogue base station.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Aug 2026
- **Updated:** 3 Aug 2026
- **Also known as:** A-518610755, ASB-A-518610755, GHSA-6g35-p5gh-6qh4, M-MOLY00741071

## What is CVE-2026-20479?

CVE-2026-20479 is a high-severity denial of service vulnerability in MediaTek, Inc. MediaTek chipset, published on 3 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In Modem, there is a possible out of bounds read due to a missing bounds check. This could lead to remote denial of service, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: MOLY00741071; Issue ID: MSV-7620.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-20479?

It affects 19 products.


Products: Mediatek Mt2735 Firmware, Mediatek Mt6833 Firmware, Mediatek Mt6853 Firmware, Mediatek Mt6855 Firmware, Mediatek Mt6873 Firmware, Mediatek Mt6875 Firmware, Mediatek Mt6877 Firmware, Mediatek Mt6880 Firmware, Mediatek Mt6883 Firmware, Mediatek Mt6885 Firmware, Mediatek Mt6889 Firmware, Mediatek Mt6890 Firmware, Mediatek Mt6891 Firmware, Mediatek Mt6893 Firmware, Mediatek Mt8675 Firmware, Mediatek Mt8771 Firmware, Mediatek Mt8791 Firmware, Mediatek Mt8791t Firmware, Mediatek Mt8797 Firmware.

## How do I fix CVE-2026-20479?

Apply the vendor's patch.

## Is CVE-2026-20479 being exploited?

There is no known exploitation of CVE-2026-20479 in the wild and no public exploit code.

## Other vulnerabilities in MediaTek, Inc. MediaTek chipset

- [CVE-2026-20433](https://insights.sbomify.com/CVE-2026-20433/): Memory corruption in MediaTek chipset (high 8.8)
- [CVE-2026-20432](https://insights.sbomify.com/CVE-2026-20432/): Memory corruption in MediaTek chipset (high 8.0)
- [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-2026-20479 and fix it if it is affected.

What it is: CVE-2026-20479 is a high-severity denial of service vulnerability in MediaTek, Inc. MediaTek chipset, published on 3 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-20479 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-2026-20479/ (Markdown: https://insights.sbomify.com/CVE-2026-20479/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-20479
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20479
- OSV: https://osv.dev/vulnerability/CVE-2026-20479

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-20479/
Summaries are generated and may contain mistakes; the official description above is the record.