The clean solution these days seems to be about querying the tracker via the JSON entrypoint. It exposes that info, and avoids relying directly on {CVE,DSA}/list. Modifying the DSA format itself is a bit involved, and could have potentially far reaching consequences.
After researching information about the JSON data, it turns out there's only one entrypoint, exposing the entire tracker data as a single JSON file. Not entirely ideal for our purpose (the download is 22M and does take some time to download), but IMO it's definitely the proper way to go about extracting the version associated to a CVE, rather than parsing the clunkier {DSA,CVE}/list files. The URL is https://security-tracker.debian.org/tracker/data/json (listed from https://security-tracker.debian.org/tracker), and using any script language against this JSON data it's quite trivial to get the version fixing a given CVE, which should be the only thing missing for the current DSA. Cheers, --Seb