Acrobat Reader DC versions 2021.005.20054 (and earlier), 2020.004.30005 (and earlier) and 2017.011.30197 (and earlier) are affected by an Uncontrolled Search Path Element vulnerability. An attacker with access to the victim's C:/ folder could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.
https://helpx.adobe.com/security/products/acrobat/apsb21-51.html