Allocation of Resources Without Limits or Throttling in Mastodon - CVE-2025-27157
Published: February 27, 2025 / Updated: April 23, 2026
Vulnerability identifier: #VU126978
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2025-27157
CWE-ID: CWE-770
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to allocation of resources without limits or throttling in the sign-up email verification feature when handling requests to change or re-request email verification during the sign-up flow. A remote attacker can send crafted requests to cause a denial of service.
The issue can be abused to send email messages to arbitrary addresses.
Affected software
Mastodon
How to mitigate CVE-2025-27157
Install security update from vendor's website.
Mastodon - addressed in versions 4.2.16, 4.3.4