{"cve":"CVE-2021-21556","nvd":{"published":"2021-06-14T19:15:08.353","modified":"2026-06-17T03:35:46.423","status":"Modified","description":"Dell PowerEdge R640, R740, R740XD, R840, R940, R940xa, MX740c, MX840c, and T640 Server BIOS contain a stack-based buffer overflow vulnerability in systems with NVDIMM-N installed. A local malicious user with high privileges may potentially exploit this vulnerability, leading to a denial of Service, arbitrary code execution, or information disclosure in UEFI or BIOS Preboot Environment.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H","score":6.7},"cwes":["CWE-787","CWE-121"],"references":["https://www.dell.com/support/kbdoc/000187958","https://www.dell.com/support/kbdoc/000187958"],"products":["dell:poweredge_mx740c_firmware","dell:poweredge_mx840c_firmware","dell:poweredge_r640_firmware","dell:poweredge_r740_firmware","dell:poweredge_r740xd_firmware","dell:poweredge_r840_firmware","dell:poweredge_r940_firmware","dell:poweredge_r940xa_firmware","dell:poweredge_t640_firmware"],"source":"nvd","synced_at":"2026-10-19T21:20:07.141963181+00:00"},"epss":{"cve":"CVE-2021-21556","score":0.00306,"percentile":0.23399,"date":"2026-10-31"},"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."]}