#VU59128 OS Command Injection in ZyXEL Communications Corp. products - CVE-2021-35031

Vulnerability identifier: #VU59128

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-35031

CWE-ID: CWE-78

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
GS1900-8
Hardware solutions / Routers & switches, VoIP, GSM, etc
XGS1210-12
Hardware solutions / Routers & switches, VoIP, GSM, etc
XGS1250-12
Hardware solutions / Routers & switches, VoIP, GSM, etc

Vendor: ZyXEL Communications Corp.

Description

The vulnerability allows a local user to execute arbitrary shell commands on the target system.

The vulnerability exists due to improper input validation in the TFTP client. A local user can pass specially crafted data to the application and execute arbitrary OS commands on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

GS1900-8: before 2.70

XGS1210-12: before 1.00

XGS1250-12: before 1.00

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External links
https://www.zyxel.com/support/Zyxel_security_advisory_for_OS_command_injection_vulnerabilities_of_switches.shtml

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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.