Vulnerability details

CVE-2026-23962

mastodon mastodon

Mastodon vulnerable to Denial of Service from a single post (client/server)

CVSS 3.1

7.5High

Official description

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.

CVSS scores

Score	Version	Source	Vector
7.5High	3.1	CVEProject cvelistV5 (CNA) (GitHub_M)	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`

Affected products

Vendor	Product	Versions	Source
mastodon	mastodon	< 4.3.18	CVEProject cvelistV5 (CNA)
mastodon	mastodon	>= 4.4.0, < 4.4.12	CVEProject cvelistV5 (CNA)
mastodon	mastodon	>= 4.5.0, < 4.5.5	CVEProject cvelistV5 (CNA)

References and advisories

https://github.com/mastodon/mastodon/security/advisories/GHSA-gg8q-rcg7-p79g x_refsource_CONFIRM
https://github.com/mastodon/mastodon/releases/tag/v4.3.18 x_refsource_MISC
https://github.com/mastodon/mastodon/releases/tag/v4.4.12 x_refsource_MISC
https://github.com/mastodon/mastodon/releases/tag/v4.5.5 x_refsource_MISC

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Details

Published: 2026-01-22
Last updated: 2026-01-23
State: Published
Assigner (CNA): GitHub_M

Exploit prediction (EPSS)

0.54%

Probability of exploitation in 30 days

45.9%

Percentile (among all CVEs)

SSVC assessment (CISA)

Automatable: Yes
Exploitation: None
Technical impact: Partial

Weaknesses (CWE)

CWE-770
Allocation of Resources Without Limits or Throttling