CVE-2026-22212: TinyOS Buffer Overflow Vulnerability

CVE-2026-22212 Overview

CVE-2026-22212 is a stack-based buffer overflow vulnerability affecting TinyOS versions up to and including 2.1.2. The vulnerability exists in the mcp2200gpio utility, which is used for GPIO operations with MCP2200 USB-to-GPIO bridge devices. The flaw is caused by unsafe use of strcpy() and strcat() functions when constructing device paths during automatic device discovery. A local attacker can exploit this vulnerability by creating specially crafted filenames under /dev/usb/, leading to stack memory corruption and application crashes.

Critical Impact

Local attackers can cause denial of service through application crashes by exploiting the buffer overflow via malicious device filenames in /dev/usb/.

Affected Products

• TinyOS versions up to and including 2.1.2
• Systems using the mcp2200gpio utility for USB device management
• Embedded systems and IoT deployments running vulnerable TinyOS versions

Discovery Timeline

• 2026-01-12 - CVE-2026-22212 published to NVD
• 2026-01-13 - Last updated in NVD database

Technical Details for CVE-2026-22212

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow). The mcp2200gpio utility performs automatic device discovery by enumerating files in the /dev/usb/ directory and constructing full device paths. The code uses unsafe string manipulation functions strcpy() and strcat() to build these paths without proper bounds checking. When a filename exceeds the expected buffer size, it overwrites adjacent stack memory, corrupting return addresses or other critical data structures.

The local attack vector requires an attacker to have user-level access to the target system to create malicious filenames in the /dev/usb/ directory. While the vulnerability does not directly enable code execution based on current analysis, the stack corruption leads to application crashes, resulting in denial of service for systems relying on the GPIO utility.

Root Cause

The root cause is the use of unsafe C string functions (strcpy() and strcat()) without proper length validation. These functions do not perform bounds checking and will continue writing data beyond the allocated buffer boundary. When the mcp2200gpio utility constructs device paths by concatenating directory paths with user-controllable filenames, no validation ensures the resulting string fits within the destination buffer.

Attack Vector

The attack requires local access to the target system. An attacker must be able to create files with specially crafted names in the /dev/usb/ directory. When the mcp2200gpio utility performs device discovery and encounters these malicious filenames, it attempts to concatenate them into a fixed-size stack buffer. If the filename is sufficiently long, it overflows the buffer and corrupts adjacent stack memory. This corruption causes the application to crash when it attempts to return from the vulnerable function or access corrupted data.

The attack mechanism involves creating filenames with lengths exceeding the internal buffer size used for path construction. Since the vulnerability is triggered during automatic device enumeration, the attacker simply needs to plant the malicious file and wait for the utility to run.

Detection Methods for CVE-2026-22212

Indicators of Compromise

• Unexpected crashes or segmentation faults from the mcp2200gpio process
• Presence of unusually long filenames in the /dev/usb/ directory
• System logs showing repeated mcp2200gpio restarts or failures
• Core dump files generated by the crashing utility

Detection Strategies

• Monitor the /dev/usb/ directory for filenames exceeding normal length thresholds
• Implement file integrity monitoring on device directories to detect suspicious file creation
• Use application crash monitoring to detect repeated mcp2200gpio failures
• Deploy endpoint detection solutions capable of identifying stack-based buffer overflow exploitation attempts

Monitoring Recommendations

• Enable audit logging for file creation events in /dev/usb/ and related device directories
• Configure crash dump analysis to identify exploitation attempts against mcp2200gpio
• Monitor system stability for IoT and embedded devices running TinyOS
• Implement process monitoring to detect abnormal termination patterns

How to Mitigate CVE-2026-22212

Immediate Actions Required

• Review all TinyOS deployments to identify systems running vulnerable versions (2.1.2 and earlier)
• Restrict file creation permissions in /dev/usb/ to trusted users and system processes
• Consider temporarily disabling automatic device discovery in mcp2200gpio if feasible
• Monitor the TinyOS GitHub repository for security updates

Patch Information

As of the last NVD update on 2026-01-13, no official patch has been documented in the CVE data. Organizations should monitor the VulnCheck advisory and the Full Disclosure post for updates on remediation guidance. Until a patch is available, implement the workarounds described below to reduce exposure.

Workarounds

• Restrict access to the /dev/usb/ directory using filesystem permissions to prevent unauthorized file creation
• Run the mcp2200gpio utility with minimal privileges using a dedicated service account
• Implement a wrapper script that validates device filenames before invoking the utility
• Consider using alternative GPIO management tools that do not have this vulnerability

# Configuration example: Restrict /dev/usb/ directory permissions
# Only allow root and gpio group to create files
sudo chown root:gpio /dev/usb/
sudo chmod 750 /dev/usb/

# Monitor for suspicious file creation attempts
sudo auditctl -w /dev/usb/ -p wa -k tinyos_gpio_monitor