CVE-2026-23962
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.52%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.52% probability · 43th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-770
- Affected
- joinmastodon/mastodon
- Source
- security-advisories@github.com
References
- https://github.com/mastodon/mastodon/releases/tag/v4.3.18Release Notes
- https://github.com/mastodon/mastodon/releases/tag/v4.4.12Release Notes
- https://github.com/mastodon/mastodon/releases/tag/v4.5.5Release Notes
- https://github.com/mastodon/mastodon/security/advisories/GHSA-gg8q-rcg7-p79gVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.