I saw multiple reports that July's Patch Tuesday fixes a vulnerability in Microsoft Defender, CVE-2020-1461. The MS article, dated 14 July 2020 says that the problem was fixed in a definition update. I found the patched file on my system, dated 4 April 2020. The article also contains an interesting note:
4. Does this update contain any additional security-related changes to functionality?
Yes. In addition to the changes that are listed for this vulnerability, this update includes defense-in-depth updates to help improve security-related features.