Vulnerability identifier: #VU50744

Vulnerability risk: Low

CVSSv3.1: 3.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-23839

CWE-ID: CWE-310

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
OpenSSL
Server applications / Encryption software

Vendor: OpenSSL Software Foundation

Description

The vulnerability allows a remote attacker to perform a MitM attack.

The vulnerability exists due to a faulty implementation of the padding check when server is configured to support SSLv2 protocol. A remote attacker can perform a MitM attack and force the server to use less secure protocols.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

OpenSSL: 1.0.2s - 1.0.2x

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External links
http://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=30919ab80a478f2d81f2e9acdcca3fa4740cd547
http://www.openssl.org/news/secadv/20210216.txt
http://www.trustwave.com/en-us/resources/security-resources/security-advisories/?fid=28459

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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.