#VU50740 NULL pointer dereference in OpenSSL

Published: 2021-02-17 | Updated: 2023-10-30

Vulnerability identifier: #VU50740

Vulnerability risk: Medium

CVSSv3.1: 5.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-23841


Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Server applications / Encryption software

Vendor: OpenSSL Software Foundation


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.

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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

External links

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.

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