CVE-2026-23962 HIGH

CVE-2026-23962: Mastodon vulnerable to Denial of Service from a single post (client/server)

Vendor Mastodon
Product mastodon
Weakness CWE-770 · Uncontrolled resource consumption
Published January 22, 2026
Last update January 22, 2026
View on NVD All CVEs

CVSS base score

7.5/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

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

What the vulnerability does

01Description

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon versions before v4.3.18, v4.4.12, and v4.5.5 do not have a limit on the maximum number of poll options for remote posts, allowing attackers to create polls with a very large amount of options, greatly increasing resource consumption. Depending on the number of poll options, an attacker can cause disproportionate resource usage in both Mastodon servers and clients, potentially causing Denial of Service either server-side or client-side. Mastodon versions v4.5.5, v4.4.12, v4.3.18 are patched.

Key dates

02Disclosure timeline

January 22, 2026 CVE published
January 22, 2026 Record updated