An issue existed in the handling of links in encrypted PDFs. This issue was addressed by adding a confirmation prompt. This issue is fixed in macOS Catalina 10.15. An attacker may be able to exfiltrate the contents of an encrypted PDF.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-8772
Reference (s):
- https://support.apple.com/kb/HT210722
- https://support.apple.com/HT210634