{"cve":"CVE-2021-27391","nvd":{"published":"2021-09-14T11:15:23.913","modified":"2026-06-17T03:44:46.327","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-120"],"references":["https://cert-portal.siemens.com/productcert/pdf/ssa-944498.pdf","https://cert-portal.siemens.com/productcert/pdf/ssa-944498.pdf"],"products":["siemens:apogee_mbc_\\(ppc\\)_\\(p2_ethernet\\)_firmware","siemens:apogee_mec_\\(ppc\\)_\\(p2_ethernet\\)_firmware","siemens:apogee_pxc_bacnet_automation_controller_firmware","siemens:apogee_pxc_compact_\\(p2_ethernet\\)_firmware","siemens:apogee_pxc_modular_\\(bacnet\\)_firmware","siemens:apogee_pxc_modular_\\(p2_ethernet\\)_firmware","siemens:talon_tc_compact_\\(bacnet\\)_firmware","siemens:talon_tc_modular_\\(bacnet\\)_firmware"],"source":"nvd","synced_at":"2026-10-19T21:23:41.316049955+00:00"},"epss":{"cve":"CVE-2021-27391","score":0.03369,"percentile":0.88752,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}