Description
Mastodon is a free, open-source social network server based on ActivityPub. In Mastodon version 4.4, support for verifiable quote posts with quote controls was added, but it is possible for an attacker to bypass these controls in Mastodon versions prior to 4.4.8 and 4.5.0-beta.2. Mastodon internally treats reblogs as statuses. Since they were not special-treated, an attacker could reblog any post, then quote their reblog, technically quoting themselves, but having the quote feature a preview of the post they did not get authorization for with all of the affordances that would be otherwise denied by the quote controls. This issue has been patched in versions 4.4.8 and 4.5.0-beta.2.
Scores
CVSS v3
4.3
EPSS
0.0005
EPSS Percentile
14.0%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
partial
Details
CWE
CWE-754
Status
published
Products (2)
joinmastodon/mastodon
4.5.0 beta1
joinmastodon/mastodon
4.4.0 - 4.4.8
Published
Oct 21, 2025
Tracked Since
Feb 18, 2026