ADDITIONAL SYSTEM INFORMATION :
MacOSX, JDK 20

A DESCRIPTION OF THE PROBLEM :
The fix addressing JDK-8295753 causes reproducible AccessControlException on the '/' folder in MacOSX. It seems the fix now requires granting full read rights to all folders on the path to a resource, something that wasn't required before.

REGRESSION : Last worked in version 17.0.7

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run provided source with enabled security manager.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Hello World!
/private/tmp/hello.txt
ACTUAL -
Hello World!
Exception in thread "main" java.security.AccessControlException: access denied ("java.io.FilePermission" "/" "read")

---------- BEGIN SOURCE ----------
Policy:
grant {
    permission java.io.FilePermission "/private/tmp", "read,write";
    permission java.io.FilePermission "/private/tmp/-", "read,write,delete";
};

Reproducer:
public static void main(String[] args) throws Exception {
        // Works
        Files.writeString(Paths.get("/private/tmp/hello.txt"), "Hello World!");
        System.out.println(Files.readString(Paths.get("/private/tmp/hello.txt")));

        // Exception
        System.out.println(Paths.get("/private/tmp/hello.txt").toRealPath(LinkOption.NOFOLLOW_LINKS));
    }
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Grant read access to all folders for a resource on the way to the root
or
Use JDK < 20
or
Don't use toRealPath.

FREQUENCY : always