Vulnerability identifier: #VU50740

Vulnerability risk: Medium

CVSSv3.1:

CVE-ID: CVE-2021-23841

CWE-ID:

Exploitation vector: Network

Exploit availability:

Vulnerable software:
OpenSSL
Server applications / Encryption software

Vendor: OpenSSL Software Foundation

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error within the X509_issuer_and_serial_hash() function when parsing the issuer field in the X509 certificate. A remote attacker can supply a specially crafted certificate, trigger a NULL pointer dereference error and perform a denial of service (DoS) attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

OpenSSL: 1.1.1 - 1.1.1i, 1.1.0 - 1.1.0l, 1.0.2 - 1.0.2x, 1.0.1 - 1.0.1u, 1.0.0 - 1.0.0t

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Fixed software versions

CPE

• cpe:2.3:a:openssl_software_foundation:openssl:1.1.1i:*:*:*:*:*:*:*

External links
http://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=6a51b9e1d0cf0bf8515f7201b68fb0a3482b3dc1
http://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=9b1129239f3ebb1d1c98ce9ed41d5c9476c47cb2
http://www.openssl.org/news/secadv/20210216.txt

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Q & A

Can this vulnerability be exploited remotely?

Is there known malware, which exploits this vulnerability?