Secure boot bypass in Cisco IOS XR

1) Improper Verification of Cryptographic Signature

EUVDB-ID: #VU105678

Risk: Low

CVSSv4.0: 5.7 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2025-20143

CWE-ID: CWE-347 - Improper Verification of Cryptographic Signature

Exploit availability: No

Description

The vulnerability allows a local user to bypass security boot protections.

The vulnerability exists due to improper cryptographic signature verification of modules in the software load process. A local user can bypass some of the integrity checks that are performed during the booting process and compromise the affected system.

This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco IOS XR Software, regardless of device configuration:

• ASR 9000 Series Aggregation Services Routers (64-bit)
• IOS XRv 9000 Routers
• Network Convergence System (NCS) 540 Series Routers that are running an NCS540-iosxr base image
• NCS 560 Series Routers
• NCS 1000 Series
• NCS 5000 Series Routers
• NCS 5500 Series Routers

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Cisco IOS XR: 7.0 - 7.9

CPE2.3

• cpe:2.3:o:cisco_systems:cisco_ios_xr:7.0:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios_xr:7.0.1:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios_xr:7.0.2:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios_xr:7.0.14:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios_xr:7.0.90:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios_xr:7.1:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios_xr:7.1.1:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios_xr:7.1.2:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios_xr:7.1.3:*:*:*:*:*:*:*
• cpe:2.3:o:cisco_systems:cisco_ios_xr:7.1.15:*:*:*:*:*:*:*

External links

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sb-lkm-zNErZjbZ
https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvx66790
https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvx66852

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.