Description

A security researcher has found a critical flaw in the popular Worldline Yomani XR payment terminal, which could enable attackers to take complete control over the terminal within less than a minute. Widely used in Swiss enterprises like grocery stores, cafes, and repair shops, the terminal features an embedded maintenance port that exposes a root shell through an unprotected serial interface. By merely plugging a serial cable via a hidden debug connector and rebooting the unit, an attacker has root access with no authentication—representing a significant threat in spite of the terminal's ostensibly secure and tamper-resistant casing. The problem here stems from a bug in the terminal's software architecture. Although the hardware is designed with robust physical defenses–such as tamper sensors and circuit-disablement mechanisms–the software aspect is not as secure. The machine operates a dual-core setup in which one core controls the Linux-based business logic and network, and the other processes sensitive card processing within a safer, encrypted context. Even though the secure core is isolated, intruders with root privileges to the Linux system could still disrupt software updates, intercept data, or install persistent malware, thus weakening the overall payment system infrastructure. In order to reduce the threat, companies operating the Yomani XR must immediately check for tampering on equipment, particularly in the region of the service hatch. Worldline must be contacted to confirm that they are operating on the most up-to-date firmware, which is said to shut down the vulnerable debug port. Use of regular security scans and physical access controls is also advised to block unauthorized access to vital payment infrastructure.