Full Report
Siemens’ User Management Component (UMC) is affected by multiple vulnerabilities that could allow an unauthenticated remote attacker to execute arbitrary code or to cause a denial of service condition. Siemens has released a new version for User Management Component (UMC) and recommends to update to the latest version. Siemens is preparing further fix versions and recommends specific countermeasures for products where fixes are not, or not yet available.
Analysis Summary
# Vulnerability: Multiple Vulnerabilities in Siemens User Management Component (UMC)
## CVE Details
- **CVE ID:** CVE-2025-40795
- **CVSS Score:** 9.8 (Critical) | CVSS:4.0: 9.3
- **CWE:** CWE-121 (Stack-based Buffer Overflow)
- **CVE ID:** CVE-2025-40796
- **CVSS Score:** 7.5 (High) | CVSS:4.0: 8.7
- **CWE:** CWE-125 (Out-of-bounds Read)
- **CVE ID:** CVE-2025-40797
- **CVSS Score:** 7.5 (High) | CVSS:4.0: 8.7
- **CWE:** CWE-125 (Out-of-bounds Read)
- **CVE ID:** CVE-2025-40798
- **CVSS Score:** 7.5 (High) | CVSS:4.0: 8.7
- **CWE:** CWE-125 (Out-of-bounds Read)
## Affected Systems
- **Products:**
- User Management Component (UMC)
- SIMATIC PCS neo (V4.1, V5.0, V6.0)
- **Versions:**
- UMC: All versions prior to V2.15.1.3
- SIMATIC PCS neo: All versions associated with the above UMC versions.
- **Configurations:** Systems where UMC is installed and reachable via the network, specifically those using 'RT Server' type or exposing management ports.
## Vulnerability Description
The Siemens User Management Component (UMC) contains several memory safety flaws. The most severe (CVE-2025-40795) is a **stack-based buffer overflow** that allows an unauthenticated remote attacker to overwrite memory by sending specially crafted packets. This can lead to arbitrary code execution (RCE) or a total system crash. The remaining three vulnerabilities (CVE-2025-40796, CVE-2025-40797, and CVE-2025-40798) involve **out-of-bounds reads**, which can be triggered remotely to cause a Denial of Service (DoS) condition by crashing the integrated UMC service.
## Exploitation
- **Status:** Not exploited (No known active exploitation or public PoC mentioned in advisory).
- **Complexity:** Low
- **Attack Vector:** Network
## Impact
- **Confidentiality:** High (due to potential RCE)
- **Integrity:** High (due to potential RCE)
- **Availability:** High (due to DoS or system crash)
## Remediation
### Patches
- **User Management Component (UMC):** Update to **V2.15.1.3** or later.
- **SIMATIC PCS neo (V6.0):** No fix currently available; follow workarounds.
- **SIMATIC PCS neo (V4.1 & V5.0):** No fix planned; follow workarounds.
### Workarounds
- **Port Blocking:** Block incoming traffic on **TCP ports 4002 and 4004** on machines where UMC is installed.
- **Partial Blocking:** If the deployment does *not* use the ‘RT Server’ type, port 4004 can be blocked across the board without impacting Agent, Server, or Ring-Server machine types.
- **Network Isolation:** Ensure industrial control systems are not exposed to the internet and are operated within a protected IT environment following Siemens’ operational guidelines.
## Detection
- **Indicators of Compromise:** Unexpected crashes of the UMC service or unauthorized remote code execution artifacts.
- **Detection methods and tools:** Monitor network traffic for unusual activity on TCP ports 4002 and 4004. Use vulnerability scanners to identify outdated UMC versions (pre-V2.15.1.3).
## References
- **Vendor Advisory:** hxxps://cert-portal.siemens[.]com/productcert/html/ssa-722410.html
- **UMC Download:** hxxps://support.industry.siemens[.]com/cs/ww/en/view/109991261/
- **Industrial Security Guidelines:** hxxps://www.siemens[.]com/cert/operational-guidelines-industrial-security