Executive Summary
Siemens Reyrolle 7SR5 protection relay systems before version 2.70 are affected by 14 critical vulnerabilities, including authentication bypass, session hijacking, and buffer overflow conditions. These vulnerabilities in the Cesanta Mongoose Web Server component allow unauthenticated remote attackers to gain administrative access, execute arbitrary code, and cause denial-of-service conditions on critical power grid protection equipment deployed worldwide. The highest severity vulnerability (CVE-2026-62645) achieves a CVSS score of 9.8, enabling complete system compromise through predictable session identifiers and missing authentication controls.
These vulnerabilities highlight the growing cybersecurity risks in operational technology (OT) environments, particularly as critical infrastructure becomes increasingly connected and exposed to network-based attacks targeting industrial control systems.
Why This Matters Now
Critical infrastructure protection systems are increasingly targeted by nation-state actors and cybercriminals, with power grid vulnerabilities posing systemic risks to national security and economic stability requiring immediate patching and enhanced OT security measures.
Attack Path Analysis
Attackers exploit multiple vulnerabilities in Siemens Reyrolle 7SR5 industrial control systems through web interface and TLS vulnerabilities to gain initial access, bypass authentication mechanisms to escalate privileges, move laterally through industrial networks, establish persistent command and control channels, exfiltrate sensitive operational data and configuration information, and ultimately impact critical power grid operations through device manipulation and service disruption.
Kill Chain Progression
This analysis maps confirmed threat intelligence to the full cloud kill chain to show where defensive gaps would emerge as an attack progresses.
Initial Compromise
Description
Attackers exploit web interface vulnerabilities (CVE-2026-62645, CVE-2024-42384) and TLS packet manipulation to crash services and bypass initial authentication mechanisms on internet-exposed industrial control systems
Related CVEs
CVE-2024-42384
CVSS 7.5Integer overflow vulnerability in Cesanta Mongoose Web Server allows attackers to send unexpected TLS packets causing segmentation faults in Siemens Reyrolle 7SR5 protective relays.
Affected Products:
Siemens Reyrolle 7SR5 – < V2.70
Exploit Status:
no public exploitCVE-2026-62645
CVSS 9.8Information exposure through web interface allows calculation of current and past session IDs, enabling authentication bypass in Siemens Reyrolle 7SR5 protective relays.
Affected Products:
Siemens Reyrolle 7SR5 – < V2.70
Exploit Status:
no public exploitCVE-2026-62646
CVSS 7.4Session identifiers generated with insufficient entropy allow remote attackers to predict valid session tokens and bypass authentication in Siemens Reyrolle 7SR5.
Affected Products:
Siemens Reyrolle 7SR5 – < V2.70
Exploit Status:
no public exploitCVE-2026-62648
CVSS 7.5Improper URL length validation in HTTP messages results in out-of-bounds write condition, allowing remote denial of service attacks on Siemens Reyrolle 7SR5.
Affected Products:
Siemens Reyrolle 7SR5 – < V2.70
Exploit Status:
no public exploitCVE-2026-62650
CVSS 8.8Improper server-side authorization allows authenticated users to bypass role-based access controls and escalate privileges to administrative level in Siemens Reyrolle 7SR5.
Affected Products:
Siemens Reyrolle 7SR5 – < V2.70
Exploit Status:
no public exploit
MITRE ATT&CK® Techniques
Exploit Public-Facing Application
Command and Scripting Interpreter
Bypass User Account Control
Disable or Modify Tools
Network Sniffing
Network Denial of Service
Hardware Additions
Potential Compliance Exposure
Mapping incident impact across multiple compliance frameworks.
CISA ZTMM 2.0 – Asset Management and Inventory
Control ID: ID.AM-1
NIS2 Directive – Cybersecurity Risk Management Measures
Control ID: Article 21
NYDFS 23 NYCRR 500 – Penetration Testing and Vulnerability Assessments
Control ID: 500.15
DORA – ICT Risk Management Framework
Control ID: Article 11
PCI DSS 4.0 – Software Security Framework
Control ID: 6.2.4
ISO 27001:2022 – Management of Technical Vulnerabilities
Control ID: A.8.8
Sector Implications
Industry-specific impact of the vulnerabilities, including operational, regulatory, and cloud security risks.
Utilities
Critical electrical grid protection systems face authentication bypass and denial-of-service vulnerabilities, potentially compromising power infrastructure reliability and operational technology security.
Oil/Energy/Solar/Greentech
Energy sector protection relay systems vulnerable to multiple critical flaws enabling unauthorized access, system crashes, and potential disruption of energy generation facilities.
Industrial Automation
Manufacturing and process control environments using Siemens protection systems exposed to session hijacking, privilege escalation, and industrial control system compromise attacks.
Government Administration
Critical infrastructure oversight agencies must address protection system vulnerabilities that could impact national security through power grid and industrial facility disruption.
Sources
- Siemens Reyrolle 7SR5https://www.cisa.gov/news-events/ics-advisories/icsa-26-258-05Verified
- Siemens Security Advisory SSA-142885https://support.industry.siemens.com/cs/ww/en/view/109772413/Verified
- Siemens Grid Security Guidelineshttps://www.siemens.com/gridsecurityVerified
Frequently Asked Questions
Cloud Native Security Fabric Mitigations and ControlsCNSF
Based on the attack progression modeled above, these are the defensive controls that would constrain each stage.
Aviatrix Zero Trust CNSF would have significantly constrained this industrial control system attack by implementing network segmentation and controlled access paths. The framework's east-west traffic controls and egress enforcement would likely have reduced the attacker's blast radius across critical infrastructure networks.
Control: Cloud Native Security Fabric (CNSF)
Mitigation: Network segmentation policies would likely have limited the attacker's ability to reach vulnerable industrial control systems by creating isolated network zones with restricted access paths.
Control: Zero Trust Segmentation
Mitigation: Identity-aware access controls would likely have constrained privilege escalation by enforcing granular permissions and limiting the scope of administrative access across segmented workloads.
Control: East-West Traffic Security
Mitigation: Microsegmentation policies would likely have constrained lateral movement by blocking unauthorized east-west communication between industrial control systems and adjacent network segments.
Control: Multicloud Visibility & Control
Mitigation: Network visibility and anomaly detection would likely have identified unauthorized communication patterns and constrained the establishment of persistent command channels across infrastructure segments.
Control: Egress Security & Policy Enforcement
Mitigation: Controlled egress policies would likely have constrained data exfiltration by limiting outbound communication paths and blocking unauthorized data transfers from industrial control system networks.
While CNSF controls may have reduced the attack scope, residual impact could still affect isolated industrial control systems within compromised network segments, though the blast radius would likely be constrained to specific operational zones.
Impact at a Glance
Affected Business Functions
- Electrical Grid Protection Systems
- Power System Monitoring
- Relay Configuration Management
- Critical Infrastructure Operations
Estimated downtime: 2 days
Estimated loss: N/A
Potential unauthorized access to power grid protection system configurations, operational data, and critical infrastructure control parameters through authentication bypass vulnerabilities
Recommended Actions
Key Takeaways & Next Steps
- • Implement Zero Trust Segmentation to isolate industrial control systems and prevent lateral movement between OT and IT networks with identity-based policy enforcement
- • Deploy Encrypted Traffic controls with high-performance encryption to protect unencrypted operational technology communications and prevent data exfiltration
- • Enable Multicloud Visibility & Control to detect anomalous interactions with industrial systems and monitor for repeated malformed requests targeting web interfaces
- • Establish Egress Security & Policy Enforcement to prevent unauthorized data exfiltration from critical infrastructure systems and block command and control communications
- • Implement Inline IPS with Suricata signatures to detect and block known exploit patterns targeting industrial control system vulnerabilities and malicious TLS packets
