CVE-2021-41853 - A Deep Dive into an Unused and Rejected CVE

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Introduction

You might come across many Common Vulnerabilities and Exposures (CVEs) every year. Some shake the cybersecurity world, while others quietly fade into obscurity. Today, we’re going to take an exclusive and simple look at CVE-2021-41853 — a vulnerability that was ultimately rejected with the message: *“This is unused.”*

We’ll unpack what that means, why it matters, and dissect the story behind it. We’ll also talk about how to analyze similar cases for your own security knowledge.

What Is CVE-2021-41853?

CVE-2021-41853 is listed on several CVE tracking sites, but it sticks out for one key reason: it was never really assigned to a real vulnerability.

The official entry just says

> REJECT — This candidate was withdrawn by its requestor. This is unused.

References

- CVE Details Page
- NIST NVD Entry

What Does “Rejected: This is unused” Mean?

Sometimes, a CVE ID is assigned in error, requested preemptively, or the underlying issue is resolved before publication. In these cases, the record is “rejected.” With CVE-2021-41853, the description shows:

REJECT
This candidate was withdrawn by its requestor.
This is unused.

TL;DR:
Someone thought there was a bug. They asked for a CVE ID.
After more investigation, they realized: “Oops, there’s really nothing to report here.”
So, the CVE was officially marked as unused.

Can I Exploit CVE-2021-41853?

No.
Unlike other CVEs, CVE-2021-41853 has no associated exploit because there is no vulnerability. It is important for security professionals not to waste time looking for patches, Proof-of-Concepts (PoCs), or exploits.

Example of a (non-existent) Exploit

# Example of what people might search for, but DOES NOT EXIST
import requests

vulnerable_url = "https://target.site/some_endpoint";
# This will NOT work, because there is no vulnerability!

payload = {"attack": "CVE-2021-41853"}
r = requests.post(vulnerable_url, data=payload)

print("Exploit sent!")  # This is just for demonstration.

Note: There is nothing to exploit—and you won’t find anything even in dark corners of the Internet.

Lessons Learned

Rejected and unused CVEs like this are part of the system to maintain integrity.

Check the official CVE page and its description.

2. Don’t panic if you see it flagged in a scan; verify if it is genuine or marked as “REJECT.”

Conclusion

CVE-2021-41853 serves as a reminder that not every CVE you see is a real threat. Always double check, stay informed, and don’t let unused entries distract you from genuine vulnerabilities that need your attention.

Timeline

Published on: 02/23/2024 21:15:10 UTC
Last modified on: 09/04/2025 00:48:06 UTC