Azure's Weakest Link – Five Full Cross-Tenant Compromises
https://www.binarysecurity.no/posts/2026/10/one-root-caseThe callback you're redirecting the user to at the end of that flow is forgeable if an attacker knows an azure tenant ID of a different customer, and putting a "Never use the tenant ID value of the tenant parameter to authenticate or authorize users" warning in the docs is only helpful as long as a way to authenticate users exists.
[2026-10-02]
beginning of curent month feels like two years ago when multiple vulns drop daily
likely been active since the inception of these capabilities
wonder if the recommendation to "add randomness to resource names" is because of this (unrelated security by obscurity lol)
Microsoft had an egregious cross-tenant vulnerability (really, how many cross-tenant vulnerabilities did other clouds have?).
Vulnerability was reported.
They fixed it - incorrectly. Reported again.
They fixed it this time... and broke the previous fix. So it's vulnerable again.
What a clown show.
Should have been addressed in the Geneva conventions.
The cloud:
Let’s see how their platform design holds up in the coming years, and if it can hold up to LLMs doing more of this same type of discovery and whether MSFT can fix it.
Reporting “theoretical” issues with validation as an Employee gets you a lot of questions as to why you were looking.
Oh well.