Overlap in CIDR

[amitjattan]

Describe the bug
There are some vnet's which got created with overlap CIDR ranges, and we can see both CIDRs are makred as associated as well.
To Reproduce
Steps to reproduce the behavior:
Not sure how to reproduce this as this is not permanent issue

Expected behavior
CIDRs shouldn't be overlapped atleast once those are associated to an existing vnets. Reservations shouldn;t evn provide those ranges

Screenshots

⚠️ Found 5 overlap(s): just adding one here for security reason

OVERLAP DETECTED:
VNet 1: ***
Address Spaces: 10.43.2.192/26

VNet 2: ***
Address Spaces: 10.43.2.192/28

Overlapping CIDRs:
- 10.43.2.192/26 <-> 10.43.2.192/28

Additional context
We have observed this behaviour for few vnets as mentioned above.

[DCMattyG]

Hey amitjattan, acknowledging this issue. I'll look into this immediately, but just out of curiosity could these vNET CIDR's have been updated after creation/association?

Right now, we can associate Virtual Networks to a Block as long as they are non-overlapping, but since Azure IPAM sits outside of Azure, there is nothing stopping someone from updating or changing the Address Space of the Virtual Network after that happens, which could definitely lead to an overlap situation like you are seeing. I'm not saying that is what happened here, but was just wondering if you've already explored that as a possibility.