IIRC it didn't just have no release notes, it explicitly claimed not to contain security patches. Although I may be misremembering or may have been misled by a

IIRC it didn't just have no release notes, it explicitly claimed not to contain security patches. Although I may be misremembering or may have been misled by an ambiguous message. https://support.apple.com/en-us/HT201222 https://support.apple.com/en-us/HT201222 lists it as being a security update but "This update has no published CVE entries." (emphasis mine) implying some nasty but embargoed security issue.