Unauthenticated throttle bypass via formatted paths
Published Nov 16, 2022 · Updated Apr 29, 2025
Improper authentication throttling in Mastodon before 4.0.0 allows remote attackers to bypass rate limits on account endpoints. Rack::Attack compares authentication paths for exact equality, while Rails accepts the same routes with format suffixes such as .html, leaving suffixed requests outside the configured throttles. No authentication is required, and repeated login, registration, password-reset, or confirmation attempts can proceed without the intended per-IP or per-account limits.
Summary
What happened
Improper authentication throttling in Mastodon before 4.0.0 allows remote attackers to bypass rate limits on account endpoints. Rack::Attack compares authentication paths for exact equality, while Rails accepts the same routes with format suffixes such as .html, leaving suffixed requests outside the configured throttles. No authentication is required, and repeated login, registration, password-reset, or confirmation attempts can proceed without the intended per-IP or per-account limits.
The record
- CVE
- CVE-2022-2166
- Published
- Nov 16, 2022
- Updated
- Apr 29, 2025
- Vendor
- Mastodon
- Product
- Mastodon
- Classifications
- CWE-307, T1110
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Nov 16, 2022CVE publishedPublication date reported by the CVE source.
- Apr 29, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=unspecified <4.0.0
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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