Acrobat Reader DC versions versions 2020.013.20074 (and earlier), 2020.001.30018 (and earlier) and 2017.011.30188 (and earlier) are affected by an memory corruption vulnerability. An unauthenticated attacker could leverage this vulnerability to cause an application denial-of-service. Exploitation of this issue requires user interaction in that a victim must open a malicious file.
https://helpx.adobe.com/security/products/acrobat/apsb21-09.html