Adobe Acrobat Reader 2017.009.20058 and earlier, 2017.008.30051 and earlier, 2015.006.30306 and earlier, and 11.0.20 and earlier has an exploitable use after free vulnerability in JavaScript engine when creating large strings. Successful exploitation could lead to arbitrary code execution.
https://helpx.adobe.com/security/products/acrobat/apsb17-24.html