How severe is CVE-2021-4300?

CVE-2021-4300 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2021-4300 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-4300?

CVE-2021-4300 affects Halcyon Project Halcyon. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-4300?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-4300 published?

CVE-2021-4300 was published on 2023-01-04 and last updated on 2026-06-17.

CVE-2021-4300

CVE-2021-4300 is a medium-severity vulnerability in Halcyon Project Halcyon with a CVSS 3.x base score of 6.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-284.

Key facts

Severity: Medium (CVSS 3.x base score 6.3)
CVSS v2: 6.5
EPSS exploit prediction: 1% (47th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-284
Affected product: Halcyon Project Halcyon
Published: 2023-01-04
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-4300?: 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.
How severe is CVE-2021-4300?: CVE-2021-4300 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2021-4300 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-4300?: CVE-2021-4300 affects Halcyon Project Halcyon. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-4300?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-4300 published?: CVE-2021-4300 was published on 2023-01-04 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:halcyon_project:halcyon:*:*:*:*:*:*:*:*

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