Vulnerability identifier: #VU23423

Vulnerability risk: Medium

CVSSv3.1: 6.2 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:P/RL:U/RC:C]

CVE-ID: CVE-2019-19521

CWE-ID: CWE-287

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
OpenBSD
Operating systems & Components / Operating system

Vendor: OpenBSD

Description

The vulnerability allows a remote attacker to bypass authentication process.

The vulnerability exists due to an error in gen/auth_subr.c and gen/authenticate.c in libc, login/login.c and xenocara/app/xenodm/greeter/verify.c when handling authentication requests via the -schallenge username. A remote attacker can bypass authentication process for daemons that use vulnerable authentication scheme (e.g. smtpd, ldapd, or radiusd).

Successful exploitation of the vulnerability may allow an attacker to gain unauthorized access to the system.

Mitigation
Cybersecurity Help is currently unaware of any official solution to address this vulnerability.

Vulnerable software versions

OpenBSD: 6.6

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External links
http://www.openwall.com/lists/oss-security/2019/12/04/5
http://www.openwall.com/lists/oss-security/2019/12/04/6
http://seclists.org/bugtraq/2019/Dec/8
http://www.openbsd.org/errata66.html
http://www.openwall.com/lists/oss-security/2019/12/04/5

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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. However, proof of concept for this vulnerability is available.