CVE-2026-20404

7.5 HIGH
Denial of Service

📋 TL;DR

This vulnerability in MediaTek modems allows remote denial of service through improper input validation. An attacker can crash the system by connecting a device to a rogue base station, requiring no user interaction or special privileges. This affects devices using vulnerable MediaTek modem chipsets.

💻 Affected Systems

Products:
  • MediaTek modem chipsets
Versions: Specific versions not detailed in advisory; check MediaTek bulletin for affected chipset models
Operating Systems: Android and other mobile OS using MediaTek modems
Default Config Vulnerable: ⚠️ Yes
Notes: Affects devices with vulnerable MediaTek modem firmware; exact device models depend on OEM implementations.

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete system crash requiring physical reboot, potentially disrupting critical communications and services on affected devices.

🟠

Likely Case

Temporary service disruption on mobile devices, dropped calls, and loss of data connectivity until system recovers or reboots.

🟢

If Mitigated

Minimal impact if devices are patched or not in range of rogue base stations, with normal operation maintained.

🌐 Internet-Facing: HIGH - Attack can be triggered remotely via rogue base stations without authentication.
🏢 Internal Only: LOW - Requires proximity to rogue base station, making internal network attacks unlikely.

🎯 Exploit Status

Public PoC: ✅ No
Weaponized: UNKNOWN
Unauthenticated Exploit: ⚠️ Yes
Complexity: MEDIUM

Requires setting up rogue base station but no authentication or user interaction needed once device connects.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patch ID: MOLY01689248

Vendor Advisory: https://corp.mediatek.com/product-security-bulletin/February-2026

Restart Required: Yes

Instructions:

1. Check device manufacturer for firmware updates. 2. Apply MediaTek modem firmware patch MOLY01689248. 3. Reboot device after update.

🔧 Temporary Workarounds

Disable automatic network selection

all

Prevent devices from automatically connecting to unknown base stations

Use network locking

all

Configure devices to only connect to trusted network operators

🧯 If You Can't Patch

  • Monitor for unusual base station connections and network disruptions
  • Implement physical security controls to prevent rogue base stations in sensitive areas

🔍 How to Verify

Check if Vulnerable:

Check modem firmware version against MediaTek advisory; contact device manufacturer for vulnerability status.

Check Version:

Device-specific; typically in Settings > About Phone > Baseband Version

Verify Fix Applied:

Verify modem firmware has been updated to version containing patch MOLY01689248.

📡 Detection & Monitoring

Log Indicators:

  • Unexpected modem resets
  • Base station connection errors
  • System crash logs

Network Indicators:

  • Devices connecting to unknown base stations
  • Sudden loss of connectivity patterns

SIEM Query:

Search for modem crash events, baseband errors, or unexpected network disconnections across mobile devices

📊 Metadata

CVE ID: CVE-2026-20404
CVSS v3 Score: 7.5 (HIGH)
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE: CWE-787
Published: February 2, 2026
Last Updated: February 4, 2026

🤖 AI-assisted analysis, reviewed for accuracy

🔗 References

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