# CVE-2026-20459: Denial of service in MediaTek chipset

> Remote attackers can cause system crashes in MediaTek chipsets by connecting a device to a rogue base station, requiring no user interaction or privileges.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/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:** 1 Jul 2026
- **Updated:** 1 Jul 2026
- **Also known as:** A-509319284, ASB-A-509319284, GHSA-67vv-7c97-f7h6, M-MOLY01816800

## What is CVE-2026-20459?

CVE-2026-20459 is a medium-severity denial of service vulnerability in MediaTek, Inc. MediaTek chipset, published on 1 Jul 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 system crash due to improper input validation. 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: MOLY01816800; Issue ID: MSV-6842.

Weakness: CWE-288 (Authentication Bypass Using an Alternate Path or Channel)

## Which versions are affected by CVE-2026-20459?


## How do I fix CVE-2026-20459?

Apply the vendor's patch.

## Is CVE-2026-20459 being exploited?

There is no known exploitation of CVE-2026-20459 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-20459 and fix it if it is affected.

What it is: CVE-2026-20459 is a medium-severity denial of service vulnerability in MediaTek, Inc. MediaTek chipset, published on 1 Jul 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-2026-20459 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-2026-20459/ (Markdown: https://insights.sbomify.com/CVE-2026-20459/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-20459
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20459
- OSV: https://osv.dev/vulnerability/CVE-2026-20459

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-20459/
Summaries are generated and may contain mistakes; the official description above is the record.