Vulnerabilities in software are tracked and logged meticulously, and one common way this happens is through CVEs (Common Vulnerabilities and Exposures). Each CVE is an identifier tying a reported security issue to a unique database entry. Today, let’s look into one such entry—CVE-2021-33138—discuss what happened, and show why not all vulnerabilities make the cut.

What is CVE-2021-33138?

Every CVE is meant to describe a unique security problem. People in cybersecurity, IT, or open source often hear about CVEs going critical or about shocking new exploits. But sometimes, a CVE is created by mistake, or the issue simply ends up being unused.

Here’s the official rejected reason for CVE-2021-33138

> REJECTED: This candidate was withdrawn by its requester. This CVE ID was unused.

That means no software was patched because of it. No security boundary was broken. In fact—the CVE itself never described a real vulnerability. It likely was created as a placeholder for a possible bug that, after review, turned out not to need fixing.

Decision – If it’s not valid, it gets marked as unused or rejected.

Here’s what the official CVE page says:

> CVE-2021-33138: REJECT Reason: This candidate was withdrawn by its requester. This CVE ID was unused.

In summary, nothing really happened! The CVE exists only as a record stating it was never used.

No Exploit, No Patch

Since there was no vulnerability, there isn’t any exploit code to show, nor any patch to demonstrate. If you’re looking for a proof-of-concept script, this is all you get:

# CVE-2021-33138 - This CVE was never used. No vulnerable software.
pass

And that’s it. You’re safest from this CVE because it doesn’t exist.

There are several reasons

- Mistaken Reports: Maybe a researcher thought they saw a vulnerability, but later realized there wasn’t one.

Placeholders: Sometimes a CVE is filed “just in case,” and never filled in.

It’s a good thing! It means the process works to filter out noise.

How Can You Tell If a CVE Is Used or Unused?

- Look it up on the MITRE CVE Database.

- MITRE CVE Record for CVE-2021-33138
- CVE Process Overview

Closing Thoughts

Not all CVEs describe dangerous flaws. Many, like CVE-2021-33138, are logged only to indicate that no action is needed. If you see such a CVE in scanners, patch notes, or lists, you can safely move on.

Being vigilant about real vulnerabilities is important—but it’s also good to know when a potential threat simply… doesn’t exist.

Timeline

Published on: 01/01/1976 00:00:00 UTC
Last modified on: 09/04/2025 00:40:35 UTC