> THEN the researcher eventually goes public.

He should have said since its not going to be fixed, he will just inform the individual companies.

Once they'd brushed him off and made it clear they were not interested in listening to him, resolving the bug, or living up to the usual expectations that researchers have in companies claiming to have bug bounties on HackerOne, I'd say they lost any reasonable expectation that he'd do that.

I'll note he did go to the effort of having the first stab at that sort of resolution, when he pushed back on HackerOne's inaccurate triage of the bug as an SPF/DKIM/DMARC email issue. He clearly understood the need for triage for programs like this, and that the HackerOne internal triage team didn't understand the actual problem, but again was rebuffed.

He didn't even "go public" as that term is normally used in bug disclosure. He didn't write it up and release and exploit when Zendesk told him it was out of scope and didn't give him any indication they considered it a problem or were planning a fix. Instead he reached out to affected companies in at least a semi private way, and those companies considered the bug serious enough to pay him 50k collectively and in at least some cases drop Zendesk altogether.

I am 100% certain that every one of the companies that paid the researched would consider the way this was handled by that researched "the best alternative to HackerOne rules 'ethical disclosure' in the face of a vendor trying to cover up serious flaws".

In an ideal world, in my opinion HackerOne should publicly revoke Zendesk's account for abusing the rules and rejecting obviously valid bug payouts.

Aren't such disputes about scope relatively common? Not sure what Hackerone can do about it.

For example, most Hackerone customers exclude denial-of-service issues because they don't want people to encourage to bring down their services with various kinds of flooding attacks. That doesn't mean that the same Hackerone customers (or their customers) wouldn't care about a single HTTP request bring down service for everyone for a couple of minutes. Email authentication issues are similar, I think: obviously on-path attacks against unencrypted email have to be out of scope, but if things are badly implemented that off-path attacks somehow work, too, then that really has to be fixed.

Of course, what you really shouldn't do as a Hackerone customer is using it as a complete replacement for your incoming security contact point. There are always going to be scope issues like that, or people unable to use Hackerone at all.

We have 2 conflicting sides of the story, who knows which one is bullshiting.

Probably the one that got mad at clients being dropped over an issue "not serious enough to triage".

When in doubt, go with the side which has been forthcoming. Zendesk didn’t publish details and wrote their post misleadingly describing it as a supply chain problem sounding almost as if they were a victim rather than the supplier of the vulnerability. It’s always possible that there are additional details which haven’t come out yet but that impression of a weasel-like PM is probably accurate.