Cisco UCS UEFI Secure Boot Bypass Vulnerability Disclosed

• •CVE-2026-20293 allows bypassing UEFI Secure Boot on Cisco UCS devices.
• •Attackers need physical access to exploit this vulnerability.
• •Cisco has released updates; immediate application is recommended.

A critical vulnerability (CVE-2026-20293) in Cisco UCS Servers and UCS-based appliances allows an unauthenticated attacker with physical access to bypass UEFI Secure Boot validation checks. This vulnerability arises from the UEFI Shell's memory write commands while Secure Boot is enabled. Attackers can exploit this by selecting the UEFI Shell boot option and modifying UEFI memory variables, potentially executing unauthorized software. Cisco has released software updates to address this issue, but no workarounds are available. Organizations using affected Cisco products are urged to apply the updates immediately to mitigate risks. The vulnerability affects various Cisco UCS models, including B-Series Blade Servers and C-Series Rack Servers. The risk is heightened due to the existence of proof-of-concept code, although active exploitation has not been confirmed.