CVE-2026-48028
Mastodon: Removal of integrity-protected JSON entries from signed activities
CVSS Score
6.5
EPSS Score
0.0%
EPSS Percentile
0th
Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, Mastodon's normalization of incoming activities signed with Linked-Data Signatures does not sufficiently protect the activities from a certain class of spoofing, allowing threat actors to remove JSON entries from valid signed activities from a third-party actor. This vulnerability is fixed in 4.5.10, 4.4.17, and 4.3.23.
| CWE | CWE-354 |
| Vendor | mastodon |
| Product | mastodon |
| Published | Jun 24, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low
Affected Versions
mastodon / mastodon
>= 4.5.0-beta.1, < 4.5.10 >= 4.4.0-beta.1, < 4.4.17 < 4.3.23