CVE-2025-27157

Mastodon's rate-limits are missing on `/auth/setup`

Description

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.

Category

5.3
CVSS
Severity: Medium
CVSS 3.1 •
EPSS 0.06%
Affected: mastodon mastodon
Published at:
Updated at:

References

Link Tags
https://github.com/mastodon/mastodon/security/advisories/GHSA-v39f-c9jj-8w7h
https://github.com/mastodon/mastodon/commit/06f879ce9bea195344ac9f71e6799eea500628ec

Frequently Asked Questions

What is the severity of CVE-2025-27157?
CVE-2025-27157 has been scored as a medium severity vulnerability.
How to fix CVE-2025-27157?
To fix CVE-2025-27157, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2025-27157 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2025-27157 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-27157?
CVE-2025-27157 affects mastodon mastodon.
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