Vulnerability identifier: #VU2088

Vulnerability risk: Low

CVSSv3.1: 4.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

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
http://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.