How can I Determine CUDA update version based on installed toolkit files?

I've installed some version of the CUDA toolkit to /usr/local/cuda. Suppose I don't have access to any information about the system, like activity logs, package management state and such - I'm only inspecting the contents of files in /usr/local/cuda. I want to determine the CUDA release version of this directory, but - I want the update number as well, e.g. I want to distinguish 12.6 update 2 from 12.6 update 0. Now, if I could download and install back-versions of CUDA, I could achieve this by examining the nvcc --version output, since that usually has both a timestamp of the build and an X.Y.Z version string. Unfortunately, the third element of that string is a number different from the update number, e.g.V12.6.85 for CUDA 12.6 update 3. How do I know that 85 is the fourth value? What I tried: * version.json has all sorts of version info, but those values again don't have a trivial correspondence to the update number. * lib64/* are a bunch of library files, some with versions, but again - no clear correspondence to the update number * include/ - couldn't find something relevant inside the headers, but maybe I wasn't looking in the right place?