CVE-2021-38258 – This vulnerability is a buffer overflow in NXP ... (How to Fix)

Q: What is the severity of CVE-2021-38258?

CVE-2021-38258 has a CVSS score of 7.8 (HIGH). This vulnerability is a buffer overflow in NXP MCUXpresso SDK's USB_HostProcessCallback() function that allows attackers to execute arbitrary code or cause denial of service. It affects embedded systems using NXP microcontrollers with the vulnerable SDK. The vulnerability requires USB host functionality to be enabled and accessible to an attacker.

📋 TL;DR

This vulnerability is a buffer overflow in NXP MCUXpresso SDK's USB_HostProcessCallback() function that allows attackers to execute arbitrary code or cause denial of service. It affects embedded systems using NXP microcontrollers with the vulnerable SDK. The vulnerability requires USB host functionality to be enabled and accessible to an attacker.

💻 Affected Systems

Products:

NXP MCUXpresso SDK

Versions: Version 2.7.0 specifically

Operating Systems: Embedded systems using NXP microcontrollers

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems with USB host functionality enabled and accessible

📦 What is this software?

Mcuxpresso Software Development Kit by Nxp

View all CVEs affecting Mcuxpresso Software Development Kit →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete device compromise, data exfiltration, or device bricking

🟠

Likely Case

Denial of service causing device crashes or instability

🟢

If Mitigated

Limited impact if USB host functionality is disabled or access is restricted

🌐 Internet-Facing: MEDIUM - Requires USB access, but could be exploited via USB-connected network interfaces

🏢 Internal Only: HIGH - USB-connected devices in internal networks could be exploited

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Requires USB access to the device, but no authentication needed once access is obtained

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Version 2.8.0 or later

Vendor Advisory: https://www.nxp.com/docs/en/security-advisory/CVE-2021-38258.html

Restart Required: Yes

Instructions:

1. Download MCUXpresso SDK v2.8.0 or later from NXP website. 2. Replace the vulnerable SDK with the updated version. 3. Recompile and redeploy firmware. 4. Restart affected devices.

🔧 Temporary Workarounds

Disable USB host functionality

all

Disable USB host support in firmware if not required

Modify firmware configuration to disable USB_HOST_ENABLE flag

Implement input validation

all

Add bounds checking in USB_HostProcessCallback() function

Add buffer size validation before processing USB data

🧯 If You Can't Patch

Physically restrict USB port access to authorized personnel only
Implement network segmentation to isolate affected devices from critical networks

🔍 How to Verify

Check if Vulnerable:

Check SDK version in project configuration files or firmware metadata for version 2.7.0

Check Version:

Check MCUXPRESSO_SDK_VERSION in project configuration or firmware header

Verify Fix Applied:

Verify SDK version is 2.8.0 or later and USB_HostProcessCallback() includes bounds checking

📡 Detection & Monitoring

Log Indicators:

USB host process crashes
Memory access violation errors
Unexpected device reboots

Network Indicators:

Unusual USB traffic patterns
Unexpected device communications after USB events

SIEM Query:

Device logs containing 'USB_HostProcessCallback' errors or memory violation alerts

📊 Metadata

CVE ID: CVE-2021-38258

CVSS v3 Score: 7.8 (HIGH)

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

CWE: CWE-120

Published: October 25, 2021

Last Updated: November 21, 2024

🔗 References

https://mcusec.github.io/vulnerabilities_details#nxp_usb Exploit,Third Party Advisory
https://mcusec.github.io/vulnerabilities_details#nxp_usb Exploit,Third Party Advisory

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