CVE-2021-27391
9.8 · CRITICALOverview
CVE-2021-27391 is a critical-severity vulnerability affecting siemens apogee_mbc_\(ppc\)_\(p2_ethernet\)_firmware. It was published on September 14, 2021 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
A vulnerability has been identified in APOGEE MBC (PPC) (P2 Ethernet) (All versions >= V2.6.3), APOGEE MEC (PPC) (P2 Ethernet) (All versions >= V2.6.3), APOGEE PXC Compact (BACnet) (All versions < V3.5.3), APOGEE PXC Compact (P2 Ethernet) (All versions >= V2.8), APOGEE PXC Modular (BACnet) (All versions < V3.5.3), APOGEE PXC Modular (P2 Ethernet) (All versions >= V2.8), TALON TC Compact (BACnet) (All versions < V3.5.3), TALON TC Modular (BACnet) (All versions < V3.5.3). The web server of affected devices lacks proper bounds checking when parsing the Host parameter in HTTP requests, which could lead to a buffer overflow. An unauthenticated remote attacker could exploit this vulnerability to execute arbitrary code on the device with root privileges.
Remediation
Check the references section for vendor advisories and patches from siemens. Update apogee_mbc_\(ppc\)_\(p2_ethernet\)_firmware to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| siemens | apogee_mbc_\(ppc\)_\(p2_ethernet\)_firmware | 0 | Affected |
| siemens | apogee_mec_\(ppc\)_\(p2_ethernet\)_firmware | 0 | Affected |
| siemens | apogee_pxc_bacnet_automation_controller_firmware | >= 0, < 3.5.3 | Affected |
| siemens | apogee_pxc_compact_\(p2_ethernet\)_firmware | 0 | Affected |
| siemens | apogee_pxc_modular_\(bacnet\)_firmware | >= 0, < 3.5.3 | Affected |
| siemens | apogee_pxc_modular_\(p2_ethernet\)_firmware | 0 | Affected |
| siemens | talon_tc_compact_\(bacnet\)_firmware | >= 0, < 3.5.3 | Affected |
| siemens | talon_tc_modular_\(bacnet\)_firmware | >= 0, < 3.5.3 | Affected |
Frequently Asked Questions
What is CVE-2021-27391?
CVE-2021-27391 is a critical-severity vulnerability affecting siemens apogee_mbc_\(ppc\)_\(p2_ethernet\)_firmware. It was published on September 14, 2021 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
How severe is CVE-2021-27391?
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-27391?
Check the references section for vendor advisories and patches from siemens. Update apogee_mbc_\(ppc\)_\(p2_ethernet\)_firmware to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-27391?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-27391 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
AI-driven PR review catches vulnerable dependencies before they ship.
Browser-based exploitation validates findings with real proof-of-concept.
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