High Express Question 156 of 226

What are the main risks of file uploads with Multer?

MERN Full Stack · Speak this in 60–90 seconds · Faridabad & Delhi NCR

PICTURE THIS: STACK VS QUEUE

StackLIFOlast in, first out

QueueFIFOfirst in, first out

Simple meaning

Attackers can upload huge files, unexpected MIME types, or stored XSS in SVG.

WHY — Express instead of guessing?

Why interviewers care about Express:

Express questions separate people

who only read docs from people who shipped.

Keep it short, concrete,

and tied to Full Stack work.

Stay structured

Name the idea, why it exists, then one short example.

Close cleanly

End with when you use it and one common pitfall.

STEPS — What happens step by step?

Before you speak the answer, walk the interviewer through these steps:

1
Attackers can upload huge
files, unexpected MIME types, or stored XSS in SVG.
2
Limit size, validate type
on magic bytes not just extension, and store files outside the web root or on object storage.
3
Never serve user uploads
as executable JavaScript.
4
Give an example
One tiny concrete case you can say aloud.
5
Common mistake
What juniors usually get wrong.
6
Close
When you pick this over the alternative.

EXAMPLE — See it in action

Here's a short line you can speak, broken into clear beats:

Say this line

“Limit size, validate type on magic bytes not just extension, and store files out”

Break into beats

Limitsizevalidatetypeonmagic

Speaking order

2987408337471632900

Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.

Key takeaway

Attackers can upload huge files, unexpected MIME types, or stored XSS in SVG. Limit size, validate type on magic bytes not just extension, and store files outside the web root or on object storage.