High (8.2) in joinmastodon mastodon. EPSS 0.5% chance of exploitation in the next 30 days.
Mastodon is a self-hosted, federated microblogging platform. Starting in version 2.6.0 and prior to versions 4.1.18 and 4.2.10, by crafting specific activities, an attacker can extend the audience of a post they do not own to other Mastodon users on a target server, thus gaining access to the contents of a post not intended for them. Versions 4.1.18 and 4.2.10 contain a patch for this issue.
Severity
CVSS 3.1
8.2 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
EPSS
0.5% chance of exploitation in the next 30 days; higher than 44% of CVEs (scores of 2026-10-31)