CVE-2026-2540: Micca KE700 Auth Bypass Vulnerability

CVE-2026-2540 Overview

The Micca KE700 system contains a critical vulnerability in its resynchronization logic that makes it susceptible to replay attacks. This authentication bypass flaw allows attackers to send two previously captured rolling codes in a specific sequence, forcing the system to accept stale rolling codes and execute commands. Successful exploitation enables an attacker to clone the alarm key, granting unauthorized access to the vehicle to unlock or lock doors.

Critical Impact

Attackers can clone vehicle alarm keys and gain unauthorized physical access to vehicles by exploiting the flawed resynchronization logic and replaying captured rolling codes.

Affected Products

• Micca KE700 Vehicle Security System

Discovery Timeline

• 2026-02-15 - CVE CVE-2026-2540 published to NVD
• 2026-02-18 - Last updated in NVD database

Technical Details for CVE-2026-2540

Vulnerability Analysis

This vulnerability is classified under CWE-288 (Authentication Bypass Using an Alternate Path or Channel). The core weakness lies in the improper implementation of rolling code resynchronization logic within the Micca KE700 vehicle security system. Rolling codes are designed to provide secure keyless entry by generating a new code for each use, preventing simple replay attacks. However, the Micca KE700's flawed implementation fails to properly validate code sequences during resynchronization events.

The attack requires adjacent network access (within wireless range of the vehicle) and can be executed without any privileges or user interaction. The vulnerability provides an attacker with limited ability to read confidential data but high ability to modify system integrity, allowing them to clone alarm keys and manipulate vehicle lock states.

Root Cause

The root cause stems from improper implementation of the rolling code resynchronization mechanism. Rolling code systems typically maintain a counter that must increment with each transmission to prevent replay attacks. During normal operation, if a key fob transmits a code that is slightly ahead of the expected sequence (due to out-of-range button presses), the receiver will resynchronize. The Micca KE700 system's resynchronization logic contains a flaw that allows attackers to manipulate this process by replaying captured codes in a specific order, effectively bypassing the anti-replay protections that rolling codes are designed to provide.

Attack Vector

The attack requires physical proximity to the target vehicle (adjacent network access) to capture wireless transmissions from the legitimate key fob. An attacker would use radio frequency capture equipment to record two or more rolling code transmissions from the target vehicle's key fob. By replaying these captured codes in a specific sequence, the attacker exploits the flawed resynchronization logic to force the system into accepting stale codes.

The attack methodology involves:

1. Positioning RF capture equipment within range of the target vehicle
2. Capturing multiple rolling code transmissions when the legitimate user operates the key fob
3. Analyzing the captured codes to determine the correct replay sequence
4. Transmitting the captured codes back to the vehicle in the specific order that triggers the resynchronization flaw
5. Successfully cloning the alarm key functionality to gain unauthorized door lock/unlock access

This attack does not require any special privileges or user interaction beyond the initial code capture phase. Technical details regarding the specific replay sequence and capture methodology are available in the ASRG Security Advisory.

Detection Methods for CVE-2026-2540

Indicators of Compromise

• Unexpected vehicle lock/unlock events occurring without the owner's key fob presence
• Multiple rapid resynchronization events in vehicle security system logs
• RF signal anomalies or unusual transmission patterns near the vehicle
• Reports of unauthorized vehicle access without signs of physical break-in

Detection Strategies

• Monitor vehicle security telemetry for unusual resynchronization patterns or frequency
• Implement RF monitoring solutions to detect replay attack attempts in fleet environments
• Review vehicle access logs for lock/unlock events that don't correlate with legitimate key fob proximity
• Deploy anomaly detection for rolling code counter irregularities

Monitoring Recommendations

• Enable detailed logging on vehicle security systems where available
• For fleet operators, implement centralized monitoring of vehicle security events
• Consider aftermarket RF monitoring solutions for high-value vehicles
• Maintain awareness of vehicle access patterns and investigate anomalies promptly

How to Mitigate CVE-2026-2540

Immediate Actions Required

• Contact Micca for firmware updates or replacement options for the KE700 system
• Consider using additional physical security measures such as steering wheel locks
• Store key fobs in RF-shielding pouches when not in use to prevent code capture
• Park vehicles in secure, monitored locations when possible

Patch Information

No vendor patch information is currently available in the CVE database. Vehicle owners should contact Micca directly regarding firmware updates or system replacement options. Additional technical details and vendor response information may be available through the ASRG Security Advisory.

Workarounds

• Use Faraday bags or RF-shielding pouches to store key fobs when not actively in use
• Avoid using the key fob in isolated areas where attackers could easily capture transmissions
• Implement secondary physical security measures such as aftermarket immobilizers or steering wheel locks
• Consider replacing the Micca KE700 system with a security system that implements more robust rolling code protections
• For fleet operators, establish parking protocols that reduce exposure to RF capture attacks