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CVE-2025-27157

MEDIUMCVSS 5.3/10EPSS 0.34%

Last modified

CVE-2025-27157 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. 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`. EPSS estimates a 0.34% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS Probability
0.34%

25.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
JoinmastodonMastodon>= 4.2.0, < 4.2.16
JoinmastodonMastodon>= 4.3.0, < 4.3.4

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2025-27157?
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.
How severe is CVE-2025-27157?
CVE-2025-27157 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.34% probability of exploitation in the next 30 days.
How do I fix CVE-2025-27157?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-27157?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST