That's why after finding the Crash, we need to enter the analysis stage

Fuzzer
↓
Crash
↓
Debugger
↓
Root Cause Analysis
↓
Bug Classification

Don't confuse Root Cause and Crash

Always keep these two separate

Crash
↓
What happened

But

Root Cause
↓
Why did it happen

For example:

Crash
↓
SIGSEGV
↓
Invalid Memory Access

The Root Cause is still unknown

We may find out after investigation

Input
↓
Unsafe Copy
↓
Buffer Overflow
↓
Memory Corruption
↓
Crash

Here we have found the root cause

From the Reverse Engineer's perspective:

When you have a Crash, keep asking yourself these questions

Where did the CPU crash

Which instruction was problematic

Which register or address was involved

Where did this value come from

What data caused this situation

Where was the first place where the wrong behavior occurred

The last question is the most important

Because the Crash may have occurred at one point but the Bug may have occurred several functions earlier

When We found a crash
We don't say we found the cause of the bug
First we find the location of the crash
Then we examine the problematic instruction, then we look at the registers and memory, then we follow the data path back to where the problem actually occurred
That is

Crash
↓
Where
↓
How
↓
Why
↓
Root Cause

And this is exactly the difference between seeing a crash and understanding a bug

@reverseengine