CVE-2025-40795 (CVSS 9.8): Critical Flaw in Siemens SIVaaS Exposes Network Share Without Authentication

CVE-2025-40795 (CVSS 9.8) is a critical flaw in Siemens SIVaaS that could expose a network share without authentication. The vulnerabilities, tracked as CVE-2025-40795 through CVE-2025-40798, affect the Siemens User Management Component (UMC) used in products like SIMATIC PCS neo and include a stack-based buffer overflow that could allow an unauthenticated remote attacker to execute arbitrary code or cause a denial of service.

According to Siemens, the UMC contains multiple vulnerabilities that could permit an unauthenticated remote attacker to execute arbitrary code or trigger a denial of service. The advisory notes that CVSS v3.1 base scores for these flaws are 9.8, placing them in the critical range, with CVE-2025-40796, CVE-2025-40797 and CVE-2025-40798 involving out-of-bounds reads.

All versions of UMC prior to V2.15.1.3 are affected, and customers are urged to update to V2.15.1.3 or later; as an interim measure, those systems not connected to a network can have TCP ports 4002 and 4004 blocked, with an additional caveat about port 4004 if the RT Server is not used.