More CVEs can also sometimes be a function of exposure; Joe Random's program probably has no CVEs but that doesn't mean it's more secure than Jane Popular's tool. In this case, however, both sudo and doas have sufficient exposure to estimate their relative security using CVEs. We can also use the CVEs to characterize the kinds of vulnerabilities each has internally, without comparing them to each other. In general, the CVEs that are discovered for sudo are more severe and damning than those discovered for doas, without respect to their relative occurance.
Sure, that makes sense. Would you also consider the re-occurrence of the same class of CVE? Like the environment variable parsing you mentioned before. If there were another CVE on that for doas would you consider it more damning than the first?
Or said another way, is the lack of CVEs for doas an indication it is more secure or just less (ab?)used?