CVE-2026-23962: Mastodon vulnerable to Denial of Service from a single post (client/server)
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.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-23962?
CVE-2026-23962 is classified as a Denial of Service vulnerability that can be exploited through specially crafted posts.
How do I fix CVE-2026-23962?
To fix CVE-2026-23962, update Mastodon to version 4.3.18, 4.4.12, or 4.5.5 or later.
Which versions of Mastodon are affected by CVE-2026-23962?
Mastodon versions prior to 4.3.18, 4.4.12, and 4.5.5 are affected by CVE-2026-23962.
What type of attack does CVE-2026-23962 facilitate?
CVE-2026-23962 facilitates a Denial of Service attack by allowing an unlimited number of poll options in posts.
Is CVE-2026-23962 a local or remote vulnerability?
CVE-2026-23962 is a remote vulnerability, allowing an attacker to exploit the issue from a distance.