Mastodon is a free, open-source social network server based on ActivityPub. Mastodon 4.3 added notifications of severed relationships, allowing end-users to inspect the relationships they lost as the result of a moderation action. The code allowing users to download lists of severed relationships for a particular event fails to check the owner of the list before returning the lost relationships.
Any registered local user can access the list of lost followers and followed users caused by any severance event, and go through all severance events this way. The leaked information does not include the name of the account which has lost follows and followers. This has been fixed in Mastodon v4.3.17, v4.4.11 and v4.5.4.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
None
No data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products 3
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Joinmastodon Mastodon
cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
|
— |
4.3.17
|
|
Joinmastodon Mastodon
cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
|
4.4.0
|
4.4.11
|
|
Joinmastodon Mastodon
cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
|
4.5.0
|
4.5.4
|
References 4
https://github.com/mastodon/mastodon/commit/68e30985ca7afdb89af1b2e9dc962e1993d…
security-advisories@github.com
https://github.com/mastodon/mastodon/commit/b2bcd34486fd6681cc0f30028086ef0f472…
security-advisories@github.com
https://github.com/mastodon/mastodon/commit/c1fb6893c5175d74c074f6f786d504c8bc6…
security-advisories@github.com
https://github.com/mastodon/mastodon/security/advisories/GHSA-ww85-x9cp-5v24
security-advisories@github.com