#VU2088 Improper input validation in OpenSSH

Vulnerability identifier: #VU2088

Vulnerability risk: Low

CVSSv4.0: 1.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: N/A

CWE-ID: CWE-264

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
OpenSSH
Server applications / Remote management servers, RDP, SSH

Vendor: OpenSSH

Description
The vulnerability allows a remote attacker to bypass certain security restrictions.

The vulnerability exists due to an error in sshd, which can be used to bypass address-based access controls if the AllowUser directive is configured with invalid CIDR address ranges.

Successful exploitation of this vulnerability may allow a remote attacker to bypass implemented access control mechanisms and perform a further attacks against vulnerable system.

Mitigation
Install the latest version of OpenSSH 7.4.

Vulnerable software versions

OpenSSH: 7.3p1

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External links
https://www.openssh.com/txt/release-7.4

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

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