Mastodon up to 4.2.15/4.3.3 /auth/setup allocation of resources

Summaryinfo

A vulnerability classified as problematic was found in Mastodon up to 4.2.15/4.3.3. This impacts an unknown function of the file /auth/setup. Such manipulation leads to allocation of resources. This vulnerability is listed as CVE-2025-27157. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Mastodon up to 4.2.15/4.3.3 and classified as problematic. Affected by this issue is an unknown function of the file /auth/setup. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. Impacted is availability. CVE summarizes:

Mastodon is a self-hosted, federated microblogging platform. Starting in version 4.2.0 and prior to versions 4.2.16 and 4.3.4, the rate limits are missing on `/auth/setup`. Without those rate limits, an attacker can craft requests that will send an email to an arbitrary addresses. Versions 4.2.16 and 4.3.4 fix the issue.

The advisory is available at github.com. This vulnerability is handled as CVE-2025-27157 since 02/19/2025. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 4.2.16 or 4.3.4 eliminates this vulnerability. Applying the patch 06f879ce9bea195344ac9f71e6799eea500628ec is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Name

• Mastodon

Version

• 4.2.0
• 4.2.1
• 4.2.2
• 4.2.3
• 4.2.4
• 4.2.5
• 4.2.6
• 4.2.7
• 4.2.8
• 4.2.9
• 4.2.10
• 4.2.11
• 4.2.12
• 4.2.13
• 4.2.14
• 4.2.15
• 4.3.0
• 4.3.1
• 4.3.2
• 4.3.3

License

• open-source

Website

• Product: https://github.com/mastodon/mastodon/

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CPE 2.2info

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