I would be tempted too, though I could bet that this will be a termination of an employment, instead of the problem being fixed.
I would like to be proven wrong on this speculation..
I'm just impatient because it's a really clever and somewhat complex hack that challenges some multi-threading and transactionability assumptions some people mande and I can't really talk about it(which I'd love to share with my peers).
And make sure your contract covers your ass, under production system testing / penetration, or something similar.
The bug that lead to me discovering the security issue was mitigated by another developer, the security issue was also deemed fixed, I am 100% it was not, but there's no way to proove it at the moment, except u production, that's why I said I was tempted to actually do it.
Anyway, there's nothing much to gain by me by antagonising another coleague, the management or the bank. It's not worth the ego boost or frustration scratch, worst case scenario, I don't patch the issue in time and the bank looses money and they start taking security more seriously.
I can understand every piece of the long string of factors that lead to this ridiculous situation where such a serious security issue is not being addressed; any one in particular is not ridiculous, but they all compound to the ridiculous of the end result.
I've fixed another ridiculous security issue in the recent past without making big waves, where only one software architect understood the seriousness of just one option in a maven config file(a whole declarative security module was not being weaved into the bytecode because somone added another module and instead of both being applied, only the most recent one was being applied).
A few months ago everybody was up in arms about a "major" security issue discovered by an auditor (you could see the settings of random users by changing an id in a url). I've just shown them you can credit money to your account, yet this is low priority and they provided a fix that I'm 100% percent sure didn't fix anything, unfortunately the functionality is down on all but the production environment. I'm tempted to just credit myself 1 monetary unit in production and just show them the statement.