Cisco UCS UEFI Shell flaw (CVE-2026-20293) lets attackers bypass Secure Boot and run unauthorized software
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Cisco disclosed CVE-2026-20293, a high-severity UEFI Secure Boot bypass in the UEFI Shell of Cisco UCS Servers and UCS-based appliances. An authenticated attacker with a user or admin role, or an unauthenticated attacker with physical access, can bypass Secure Boot validation and execute unauthorized software. Cisco has released software updates, and no workarounds exist. The article does not report exploitation in the wild.
Detalhes técnicos
The root cause is that memory write commands remain available in the UEFI Shell while UEFI Secure Boot is enabled. An attacker selects the UEFI Shell boot option at boot time and uses shell commands to modify UEFI memory variables. A successful exploit lets the attacker manipulate the preboot environment, overwrite Secure Boot-related memory values and run unauthorized software on the device. Cisco rates the Security Impact as High.
Remediação
Apply the Cisco software updates that address the vulnerability, as described in advisory cisco-sa-ucs-uefi-sb-bypass-eb6xC5GW. No workarounds are available.
Linha do tempo
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sec.cloudapps.cisco.com ↗ · pub. 13/10/2026 18:05 · coletado 19/10 18:01 primeiro registro só resumo do feed
Cisco UCS UEFI Shell flaw (CVE-2026-20293) lets attackers bypass Secure Boot and run unauthorized software
ler a análise desta fonte ocultar
Cisco disclosed CVE-2026-20293, a high-severity UEFI Secure Boot bypass in the UEFI Shell of Cisco UCS Servers and UCS-based appliances. An authenticated attacker with a user or admin role, or an unauthenticated attacker with physical access, can bypass Secure Boot validation and execute unauthorized software. Cisco has released software updates, and no workarounds exist. The article does not report exploitation in the wild.
Technical Details
The root cause is that memory write commands remain available in the UEFI Shell while UEFI Secure Boot is enabled. An attacker selects the UEFI Shell boot option at boot time and uses shell commands to modify UEFI memory variables. A successful exploit lets the attacker manipulate the preboot environment, overwrite Secure Boot-related memory values and run unauthorized software on the device. Cisco rates the Security Impact as High.
Remediation
Apply the Cisco software updates that address the vulnerability, as described in advisory cisco-sa-ucs-uefi-sb-bypass-eb6xC5GW. No workarounds are available.