The vulnerability resides in the monitored_item_event_filter_treatment_bs__init_event_filter_ctx_and_result function within subscription_mgr.c. Manipulating the EventFilter argument triggers a use-after-free, enabling an attacker to read or write freed memory. This flaw satisfies both buffer overflow (CWE‑119) and use‑after‑free (CWE‑416) weaknesses. The description notes that an attacker can remotely trigger the exploit and that an exploit is publicly available, implying it can be weaponized without needing privileged local access.

Affected systems are all instances of Systerel S2OPC up to and including version 1.7.3. The vulnerability is specific to the subscription manager module and applies to clients and servers that process subscription event filters. The exact function name is monitored_item_event_filter_treatment_bs__init_event_filter_ctx_and_result in src/ClientServer/services/bgenc/subscription_mgr.c.

The CVSS score is 5.3, indicating a moderate severity. EPSS is unavailable, so current exploitation likelihood cannot be quantified, but the presence of a publicly available exploit and the statement that it may be used raise concern. The flaw is not listed in the CISA KEV catalog. Given that the attack can be performed remotely, a principled assessment suggests that the risk warrants prompt remediation.