CVE-2025-27157

5.3 MEDIUM 0.4% exploit odds Fix listed Denial of service

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in. Limited direct impact.
Exploit odds: 0.4% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2025-02-27 17:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 09:03 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.4% in the next 30 days (EPSS).
Severity: 5.3 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2025-02-27 17:15 UTC
Last modified: 2026-06-17 09:03 UTC
Exploit probability: 0.4% · EPSS, next 30 days
Weakness: CWE-770 · Allocation without limits
Record status: Analyzed

Affected

Joinmastodon Mastodon < 4.2.16
Joinmastodon Mastodon < 4.3.4

Attack profile CVSS 3.1 · 5.3

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: Low

Raw vector

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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2025-27157.md and follow it. Check whether this project is affected by CVE-2025-27157. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record