CVE-2021-33100 - What You Need To Know (And Why It Was Rejected)

Published: June 2024
Author: AI Security Writer


CVE numbers are used to track and catalog cybersecurity vulnerabilities — but not all of them actually become real threats. Sometimes, a CVE gets issued ahead of the full details, or for a potential issue that gets resolved before it’s ever exploited. One interesting case is CVE-2021-33100.

Let’s dig into what this identifier was for, why it didn’t turn into something dangerous, and what that means for security folks.

What is CVE-2021-33100?

When you first look up CVE-2021-33100 in vulnerability databases, you’ll find little more than an empty shell.

Here is the official CVE entry

> Description: This candidate was withdrawn by its CNA. Further information: this is unused.

After this, no further technical details appear. So what happened?

To understand CVE-2021-33100, it helps to know how the system works

- A software vendor, researcher, or CNA (CVE Numbering Authority) requests a CVE ID for a possible vulnerability.

If a CVE was assigned in error or is not needed, it is "REJECTED" in databases.

For CVE-2021-33100, here’s the raw data block from NIST NVD (“National Vulnerability Database”):

MITRE CVE Dictionary Entry: 
CVE-2021-33100  
 REJECT   
Reason: This candidate was withdrawn by its CNA. Further information: This is unused.

*Original Reference – NIST NVD Entry*

Why Was CVE-2021-33100 Rejected?

The official reason for rejection of this CVE is simple: "This is unused."

The issue was fixed privately and never posed a public risk.

There are no source code patches, exploit codes, or advisories linked to CVE-2021-33100 anywhere on the internet or in industry mailing lists.

Is There Any Exploit Code?

No. Since the CVE was rejected as unused, there is no proof-of-concept or exploit associated with it. If you search for exploit details or code snippets, you simply won't find anything legitimate.

A typical (but for this CVE imaginary) exploit snippet might look like

# This is a placeholder.
# No code exists for CVE-2021-33100.

raise Exception("No vulnerability found for CVE-2021-33100")

If anyone claims to have an exploit for CVE-2021-33100, treat it with suspicion — it’s likely a scam or confusion.

Monitor CVE status: Check official databases to see if a CVE is rejected or active.

- Don’t waste time: If a CVE is rejected as unused, you don’t need to patch or mitigate anything.
- Stay alert: Just because one vulnerability turns out to be nothing doesn’t mean others won’t be real threats.

Sometimes, rejected CVEs get recycled for different vulnerabilities with new numbers — but "unused" ones like this usually fade away quietly.

References

- Official CVE Record: CVE-2021-33100
- NIST National Vulnerability Database: CVE-2021-33100
- How CVEs Work (MITRE Reference)

The Takeaway

CVE-2021-33100 is a non-event:
There was never a real vulnerability, so you can cross this one off your worry list.

But it’s a good reminder that the cybersecurity world is full of moving parts. Not every warning turns into a threat — but it pays to check the official record before worrying or acting.

If you run into "rejected" CVEs, remember:

Timeline

Published on: 02/23/2024 21:15:08 UTC
Last modified on: 02/26/2025 06:26:22 UTC