CVE-2021-32486 – This vulnerability is a heap buffer overflow in... (How to Fix)

Q: What is the severity of CVE-2021-32486?

CVE-2021-32486 has a CVSS score of 7.5 (HIGH). This vulnerability is a heap buffer overflow in the 2G Radio Resource Management (RRM) component of MediaTek modems. It allows remote attackers to cause a system crash (denial of service) without requiring user interaction or special privileges. Affected systems include devices using vulnerable MediaTek modem chipsets.

📋 TL;DR

This vulnerability is a heap buffer overflow in the 2G Radio Resource Management (RRM) component of MediaTek modems. It allows remote attackers to cause a system crash (denial of service) without requiring user interaction or special privileges. Affected systems include devices using vulnerable MediaTek modem chipsets.

💻 Affected Systems

Products:

MediaTek modem chipsets with 2G RRM functionality

Versions: Specific versions not publicly detailed; affected by MOLY00500621 patch

Operating Systems: Android and other OS using MediaTek modems

Default Config Vulnerable: ⚠️ Yes

Notes: Affects devices with 2G cellular capability using vulnerable MediaTek modem firmware.

📦 What is this software?

Modem by Mediatek

View all CVEs affecting Modem →

Modem by Mediatek

View all CVEs affecting Modem →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete system crash requiring hardware reset, potentially disrupting all cellular connectivity functions on the device.

🟠

Likely Case

Temporary denial of service affecting cellular connectivity until system recovery or reboot.

🟢

If Mitigated

No impact if patched; unpatched systems remain vulnerable to remote DoS attacks.

🌐 Internet-Facing: HIGH - Exploitable remotely via cellular network without authentication.

🏢 Internal Only: LOW - Primarily affects cellular network interfaces, not typical internal network interfaces.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Requires sending specially crafted 2G network packets to vulnerable modem.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Patch ID: MOLY00500621

Vendor Advisory: https://corp.mediatek.com/product-security-bulletin/September-2021

Restart Required: Yes

Instructions:

1. Contact device manufacturer for firmware updates. 2. Apply MediaTek modem firmware patch MOLY00500621. 3. Reboot device after patch installation.

🔧 Temporary Workarounds

Disable 2G Network Mode

android

Force device to use 3G/4G/5G only to avoid 2G RRM component exposure

Settings > Network & Internet > Mobile network > Preferred network type > Select 3G/4G/5G only

🧯 If You Can't Patch

Isolate vulnerable devices from untrusted cellular networks
Implement network monitoring for abnormal 2G traffic patterns

🔍 How to Verify

Check if Vulnerable:

Check modem firmware version against MediaTek security bulletin; devices with patch MOLY00500621 applied are fixed.

Check Version:

Device-specific; typically requires manufacturer diagnostic tools or system logs.

Verify Fix Applied:

Verify modem firmware includes patch MOLY00500621 via device diagnostic tools or manufacturer verification.

📡 Detection & Monitoring

Log Indicators:

Modem crash logs
Unexpected modem resets
2G RRM error messages

Network Indicators:

Abnormal 2G network traffic patterns
Unexpected 2G protocol messages

SIEM Query:

Search for modem crash events or 2G RRM error codes in device/system logs

📊 Metadata

CVE ID: CVE-2021-32486

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: September 9, 2021

Last Updated: November 21, 2024

🔗 References

https://corp.mediatek.com/product-security-bulletin/September-2021 Vendor Advisory
https://corp.mediatek.com/product-security-bulletin/September-2021 Vendor Advisory

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