Vulnerability identifier: #VU51732

Vulnerability risk: Medium

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-3450

CWE-ID: CWE-254

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 bypass implemented security restrictions.

The vulnerability exists due to an error in implementation of the X509_V_FLAG_X509_STRICT flag allows an attacker to overwrite a valid CA certificate using any non-CA certificate in the chain. As a result, a remote attacker can perform MitM attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

OpenSSL: 1.1.1h - 1.1.1j

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External links
http://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=2a40b7bc7b94dd7de897a74571e7024f0cf0d63b
http://www.openssl.org/news/secadv/20210325.txt

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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.