CVE-2021-21057
Acrobat Reader DC versions versions 2020.013.20074 (and earlier), 2020.001.30018 (and earlier) and 2017.011.30188 (and earlier) are affected by a null pointer dereference vulnerability when parsing a specially crafted PDF file. An unauthenticated attacker could leverage this vulnerability to achieve denial of service in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.
Source: CVE-2021-21057