Allocation of Resources Without Limits or Throttling in Mastodon - CVE-2025-54879
Published: April 23, 2026
Vulnerability identifier: #VU126982
CSH Severity: Medium
CVSS v4.0: 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/E:U/U:Green
CVE-ID: CVE-2025-54879
CWE-ID: CWE-770
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Mastodon
Affected software:
Mastodon
Mastodon
Detailed vulnerability description
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 confirmation email throttle for the /auth/confirmation endpoint when handling confirmation email requests. A remote attacker can send repeated POST requests with the same email address to cause a denial of service.
By rotating IP addresses, requests can avoid the remaining IP-based throttle and target unconfirmed email addresses.
How to mitigate CVE-2025-54879
Install security update from vendor's website.