CVE-2025-54879
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-08-06

Last updated on: 2025-08-26

Assigner: GitHub, Inc.

Description
Mastodon is a free, open-source social network server based on ActivityPub Mastodon which facilitates LDAP configuration for authentication. In versions 3.1.5 through 4.2.24, 4.3.0 through 4.3.11 and 4.4.0 through 4.4.3, Mastodon's rate-limiting system has a critical configuration error where the email-based throttle for confirmation emails incorrectly checks the password reset path instead of the confirmation path, effectively disabling per-email limits for confirmation requests. This allows attackers to bypass rate limits by rotating IP addresses and send unlimited confirmation emails to any email address, as only a weak IP-based throttle (25 requests per 5 minutes) remains active. The vulnerability enables denial-of-service attacks that can overwhelm mail queues and facilitate user harassment through confirmation email spam. This is fixed in versions 4.2.24, 4.3.11 and 4.4.3.
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Meta Information
Published
2025-08-06
Last Modified
2025-08-26
Generated
2026-05-06
AI Q&A
2025-08-06
EPSS Evaluated
2026-05-05
NVD
Affected Vendors & Products
Showing 3 associated CPEs
Vendor Product Version / Range
joinmastodon mastodon From 3.1.5 (inc) to 4.2.24 (exc)
joinmastodon mastodon From 4.3.0 (inc) to 4.3.11 (exc)
joinmastodon mastodon From 4.4.0 (inc) to 4.4.3 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-770 The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability in Mastodon affects its rate-limiting system for confirmation emails. Due to a configuration error, the system checks the password reset path instead of the confirmation path for email-based throttling. As a result, the per-email limits for confirmation requests are effectively disabled, allowing attackers to bypass rate limits by rotating IP addresses and send unlimited confirmation emails to any email address. Only a weak IP-based throttle remains active.


How can this vulnerability impact me? :

The vulnerability can lead to denial-of-service attacks by overwhelming mail queues with excessive confirmation emails. It can also facilitate user harassment through spam confirmation emails sent to any email address without effective rate limiting.


What immediate steps should I take to mitigate this vulnerability?

Upgrade Mastodon to version 4.2.24, 4.3.11, or 4.4.3 or later, where the rate-limiting configuration error has been fixed. Until the upgrade, monitor and limit confirmation email requests manually to prevent abuse and consider implementing additional rate-limiting controls at the network or application level to mitigate spam and denial-of-service risks.


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