Vulnerability identifier: #VU50380

Vulnerability risk: Low

CVSSv3.1: 6.8 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-1244

CWE-ID: CWE-347

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Cisco Network Convergence System 5000 Series
Hardware solutions / Routers & switches, VoIP, GSM, etc
Cisco 8000 Series Routers
Hardware solutions / Routers & switches, VoIP, GSM, etc
Cisco ASR 9000 Series Aggregation Services Routers
Hardware solutions / Routers & switches, VoIP, GSM, etc

Vendor:

Description

The vulnerability allows a local user to bypass implemented security restrictions.

Multiple vulnerabilities in Cisco Network Convergence System (NCS) 540 Series Routers, only when running Cisco IOS XR NCS540L software images, and Cisco IOS XR Software for the Cisco 8000 Series Routers due to an unlocked version of GRUB boot loader on an affected device. Unsigned script within the ISO image is not verified during system upgrade before it is executed. A local user can modifying the boot process from the GRUB menu and bypass the boot chain of trust.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

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External links
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ioxr-l-zNhcGCBt
http://bst.cloudapps.cisco.com/bugsearch/bug/CSCvr07463

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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.