The vulnerability arises from the availability of memory write commands in the UEFI Shell while Secure Boot is enabled. An attacker can select the UEFI Shell boot option at startup and use shell commands to write to UEFI memory variables. The result is a bypass of Secure Boot validation, allowing the attacker to modify the preboot environment, overwrite Secure Boot‑related memory values, and execute unauthorized firmware or code. This flaw directly compromises the integrity of the system’s pre‑boot environment, potentially enabling persistent root-level malware.

The affected products are Cisco Enterprise NFV Infrastructure Software, Cisco Unified Computing System (Managed), Cisco Unified Computing System (Standalone), and Cisco Unified Computing System E‑Series Software (UCSE). All versions of these UEFI firmware implementations that include the vulnerable Shell interface are impacted; specific version ranges are not listed in the data.

The CVSS score of 7.1 indicates a moderate to high severity. The EPSS score is not available, so the current probability of exploitation cannot be quantified from the public data, and the vulnerability is not listed in CISA's KEV catalog. The likely attack vector requires either authenticated access with user or admin credentials or physical access to the device at boot time. The flaw permits privileged attackers to modify critical firmware variables, and once bypassed, the attacker can run arbitrary code before the operating system loads.