What’s Vulnerable › Vulnerabilities
CVE-2026-20293: Cisco UCS and UCS-Based Appliances UEFI Shell Secure Boot Bypass Vulnerability
- Severity: high (CVSS 7.1 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.2% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-09-08 · updated 2026-10-26
- Weakness: CWE-749
Description
A vulnerability in the Unified Extensible Firmware Interface (UEFI) Shell implementation of Cisco UCS Servers and UCS-based appliances could allow an authenticated attacker with valid credentials for a user account with the role of user or admin or an unauthenticated attacker with physical access to an affected device to bypass UEFI Secure Boot validation checks and execute unauthorized software. This vulnerability is due to the availability of memory write commands in the UEFI Shell while UEFI Secure Boot is enabled on a device. An attacker could exploit this vulnerability by selecting the UEFI Shell boot option at boot time and using available shell commands to modify UEFI memory variables. A successful exploit could allow the attacker to manipulate the preboot environment, overwrite UEFI Secure Boot-related memory values, and execute unauthorized software on the affected device.
Affected products
- Cisco Enterprise NFV Infrastructure Software: 3.3.1, 3.4.1, 3.5.1, 3.5.2, 3.6.1, 3.6.2 (+59)
- Cisco Unified Computing System (Managed): 4.0(1a), 4.0(1b), 4.0(1c), 4.0(1d), 4.0(2a), 4.0(2b) (+228)
- Cisco Unified Computing System E-Series Software: 4.11.1, 4.12.1, 4.12.2, 4.15.2, 4.15.3, 4.15.4
- Cisco Enterprise NFV Infrastructure Software: 4.1.1, 3.9.1, 3.5.2, 3.12.2, 3.6.2, 3.9.2 (+59)
- Cisco Unified Computing System (Managed): 4.0(1a), 4.1(1a), 4.1(1b), 4.0(4h), 4.1(1c), 4.0(4e) (+234)
In the news
References
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