CVE-2025-20634 – This critical vulnerability in MediaTek modems ... (How to Fix)

Q: What is the severity of CVE-2025-20634?

CVE-2025-20634 has a CVSS score of 9.8 (CRITICAL). This critical vulnerability in MediaTek modems allows remote code execution when a device connects to a malicious base station. Attackers can exploit an out-of-bounds write flaw to execute arbitrary code without user interaction. All devices with affected MediaTek modem chips are vulnerable.

📋 TL;DR

This critical vulnerability in MediaTek modems allows remote code execution when a device connects to a malicious base station. Attackers can exploit an out-of-bounds write flaw to execute arbitrary code without user interaction. All devices with affected MediaTek modem chips are vulnerable.

💻 Affected Systems

Products:

MediaTek modem chips

Versions: Specific versions not publicly detailed in advisory

Operating Systems: Android and other OS using affected MediaTek modems

Default Config Vulnerable: ⚠️ Yes

Notes: Affects smartphones, tablets, IoT devices, and other products with vulnerable MediaTek modem chips. Exact device models not specified in public advisory.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete device compromise allowing attackers to install persistent malware, steal sensitive data, or use device as botnet node.

🟠

Likely Case

Targeted attacks against specific individuals or organizations using rogue base stations in proximity to victims.

🟢

If Mitigated

Limited impact if devices are patched before connecting to untrusted networks or if network-level protections block malicious base stations.

🌐 Internet-Facing: HIGH - Exploitation requires only connection to rogue base station, which can be deployed anywhere.

🏢 Internal Only: MEDIUM - Internal networks typically don't have rogue base stations, but attackers could deploy them near facilities.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires attacker to operate rogue base station, which requires specialized equipment but is feasible for determined attackers.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patch ID: MOLY01289384

Vendor Advisory: https://corp.mediatek.com/product-security-bulletin/February-2025

Restart Required: Yes

Instructions:

1. Contact device manufacturer for firmware updates. 2. Apply MediaTek-provided modem firmware patch. 3. Reboot device after patch installation. 4. Verify patch via modem firmware version check.

🔧 Temporary Workarounds

Disable automatic network selection

all

Prevent devices from automatically connecting to unknown base stations

Use trusted networks only

all

Configure devices to connect only to known, trusted cellular networks

🧯 If You Can't Patch

Physically isolate devices from untrusted cellular networks
Implement network monitoring for suspicious base station connections

🔍 How to Verify

Check if Vulnerable:

Check device specifications for MediaTek modem and contact manufacturer for vulnerability status

Check Version:

Manufacturer-specific commands vary by device; check with OEM

Verify Fix Applied:

Verify modem firmware version includes patch MOLY01289384 via manufacturer tools

📡 Detection & Monitoring

Log Indicators:

Unexpected modem firmware crashes
Suspicious base station connections in modem logs

Network Indicators:

Connections to unknown base station IDs
Unusual cellular network behavior

SIEM Query:

Search for modem error codes or unexpected base station handoffs in device logs

📊 Metadata

CVE ID: CVE-2025-20634

CVSS v3 Score: 9.8 (CRITICAL)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-787

EPSS Score: 0.84% exploit probability (74.3th percentile)

Published: February 3, 2025

Last Updated: February 17, 2026

🔗 References

https://corp.mediatek.com/product-security-bulletin/February-2025 Vendor Advisory

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