When digging through public CVE (Common Vulnerabilities and Exposures) databases, security professionals and system administrators might encounter CVE identifiers that look serious at first glance but, on closer inspection, carry a status of “REJECTED” or “UNUSED.” One such case is CVE-2021-3885. In this long-read, we’ll explain what went wrong, why this specific CVE is marked as “Unused,” and how you should handle similar entries during your vulnerability management processes.

What is CVE-2021-3885?

CVE-2021-3885 was reserved for public use to identify a potential security vulnerability. However, after further investigation by the parties involved (the requester or the CNA - Common Vulnerabilities and Exposures Numbering Authority), it was determined that this CVE should not have been assigned.

If you look up the entry for CVE-2021-3885 on the official MITRE database, you’ll find

> REJECTED
> This candidate has been withdrawn by its submitter. It is an unused candidate that had been announced earlier.

Source: MITRE CVE page for CVE-2021-3885

What does “unused” mean?

In the context of the CVE database, “unused” simply means the identifier was allocated, but never linked to a real vulnerability. This might happen for several reasons:

What If You Find a “REJECTED” CVE in Your Scanner Results?

With an ever-growing pool of CVEs and automated tools pulling in every identifier, it’s not unusual to see a rejected or unused CVE pop up in your vulnerability assessment reports.

Here’s what you should do

1. Take a breath: A rejected CVE is not a red flag, but rather a sign of careful review in the CVE process.
2. Do your homework: Double-check the links and references. If the CVE’s official status is “REJECTED” or notes “unused,” there is no exploitable vulnerability associated with it.
3. Document the finding: Note for your records or ticketing system that the CVE is not valid as per MITRE/NVD.
4. Inform your team: If others are scanning and see this, let them know to ignore this CVE in your risk analysis or patching schedule.

What *Doesn’t* Exist: Exploit and Code Snippet

Unlike confirmed security vulnerabilities, rejected and unused CVEs have no exploit code, PoC (proof of concept), or patches to share. There never was a real-world attack scenario.

For the sake of illustration, here’s what you might see in a scanner

Vulnerability ID: CVE-2021-3885
Status: REJECTED (Unused - no vulnerability exists)
Mitigations: None required
References:
    https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3885

And a meaningless “exploit” code block might look like this—doing literally nothing

# This is a placeholder. There is no exploit for CVE-2021-3885.
print("No vulnerability. No exploit. All clear!")

The Importance of Well-Maintained Vulnerability Databases

Rejected CVEs serve an important purpose. By keeping a clear record of which CVEs are unused, researchers, vendors, and end users can avoid confusion and prevent double-reporting or unnecessary panic. It echoes the principle of transparency in infosec: showing not only what *is* a risk, but also what *is not*.

References

- CVE-2021-3885 on MITRE
- CVE FAQ - What does REJECTED mean?
- National Vulnerability Database Entry

Conclusion

If you see a scanner warning about CVE-2021-3885, you can safely ignore it. There never was a vulnerability attached to this CVE, so there’s nothing to patch, mitigate, or exploit. Use this as a case study in why it pays to check the official databases and understand the nuances of cybersecurity reporting!

Timeline

Published on: 02/23/2024 21:15:10 UTC
Last modified on: 09/04/2025 00:46:31 UTC