An untrusted search path vulnerability in B&R Industrial Automation’s APROL software allows a process or application to load and execute an executable that is not fully controlled by the system. The flaw is identified as CWE‑426 and carries a CVSS score of 8.4, indicating that an exploited path could permit the execution of arbitrary code. The vulnerability is limited to the way APROL resolves external binaries, so an attacker who can control the search order or supply a named executable could replace a legitimate binary with a malicious one, thereby potentially gaining the privileges of the running process.

All installations of APROL from B&R Industrial Automation GmbH that use a release older than R 4.4‑01P5 are vulnerable. Every build preceding this release contains the untrusted search path issue, making any system without the update susceptible to exploitation.

The severity score signals a high risk, yet the EPSS score of less than 1 % and the absence of a listing in CISA KEV suggest that widespread exploitation is currently unlikely. Exploitation requires an attacker to influence the mediator that APROL uses to locate command executables – for example by placing a malicious file in a directory that APROL scans or by altering certain environment variables. If successful, the attacker can run code with the same permissions as the APROL process, which may lead to privilege escalation or further system compromise.