CVE-2021-4300

Name: CVE-2021-4300
Creator: NVD / NIST
Published: 2023-01-04T22:15:08.903+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 0.66%

Last modified Jun 17, 2026

CVE-2021-4300 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. A vulnerability has been found in ghostlander Halcyon and classified as critical. Affected by this vulnerability is the function CBlock::AddToBlockIndex of the file src/main.cpp of the component Block Verification. EPSS estimates a 0.66% chance of exploitation in the next 30 days.

Description

A vulnerability has been found in ghostlander Halcyon and classified as critical. Affected by this vulnerability is the function CBlock::AddToBlockIndex of the file src/main.cpp of the component Block Verification. The manipulation leads to improper access controls. The attack can be launched remotely. Upgrading to version 1.1.1.0-hal is able to address this issue. The identifier of the patch is 0675b25ae9cc10b5fdc8ea3a32c642979762d45e. It is recommended to upgrade the affected component. The identifier VDB-217417 was assigned to this vulnerability.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.66%

46.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-284

Affected Software

Vendor	Product	Versions
Halcyon Project	Halcyon	< 1.1.1.0

References

https://github.com/ghostlander/Halcyon/commit/0675b25ae9cc10b5fdc8ea3a32c642979762d45ePatch
https://github.com/ghostlander/Halcyon/releases/tag/v1.1.1.0-halRelease Notes
https://vuldb.com/?ctiid.217417Permissions Required, Third Party Advisory
https://vuldb.com/?id.217417Permissions Required, Third Party Advisory
https://github.com/ghostlander/Halcyon/commit/0675b25ae9cc10b5fdc8ea3a32c642979762d45ePatch
https://github.com/ghostlander/Halcyon/releases/tag/v1.1.1.0-halRelease Notes
https://vuldb.com/?ctiid.217417Permissions Required, Third Party Advisory
https://vuldb.com/?id.217417Permissions Required, Third Party Advisory

Timeline

Published: Jan 4, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-4300?

How severe is CVE-2021-4300?

CVE-2021-4300 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.66% probability of exploitation in the next 30 days.

How do I fix CVE-2021-4300?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-4300?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST