CVE-2026-34021 describes an authentication bypass vulnerability in the Wertheim SafeController 5400 microcontroller used in safe deposit locker systems. The device communicates over RS-485 without cryptographic safeguards, enabling attackers who can access the communication path to sniff and replay previously captured messages. This replay capability can be exploited to spoof commands such as disabling the safe alarm, undermining the security of vault rooms. The vulnerability is categorized under CWE-294 (Authentication Bypass) and has a CVSS 4.0 base score of 8.6, indicating high severity. No vendor advisory or patch information is currently available, and no known exploits in the wild have been reported.

An attacker with access to the RS-485 communication channel can perform replay attacks to bypass authentication controls. This can result in continuous deactivation of the safe alarm system, potentially allowing unauthorized access or tampering with the vault without triggering alarms. The lack of cryptographic protection on the communication link is the root cause of this vulnerability.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict physical and network access to the RS-485 communication path to prevent attackers from capturing or injecting messages. Monitor for unusual alarm deactivation patterns as a potential indicator of exploitation.