CVE-2026-48028 Details
Description
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.
A vulnerability in Mastodon prior to versions 4.5.10, 4.4.17, and 4.3.23 allows for the removal of JSON entries from valid signed activities, due to inadequate protection against a specific type of spoofing in the normalization of incoming activities signed with Linked-Data Signatures. This issue enables threat actors to selectively hide parts of a signed activity, making it appear complete to the Mastodon server, as long as they have access to the original signed activity object. The vulnerability can be exploited by obtaining the signed activity through various means, such as inbox forwarding or relays.
Users can upgrade to Mastodon versions 4.5.10, 4.4.17, or 4.3.23 to address this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jun 24, 2026CISA-ADP
Assessed Jun 25, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/mastodon/mastodon/security/advisories/GHSA-53m7-2wrh-q839 | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-354 | Improper Validation of Integrity Check Value | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Mastodon | < v4.5.10 (semver) < v4.4.17 (semver) < v4.3.23 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 25, 2026 | CVE Modified | CISA-ADP |
| Jun 24, 2026 | New CVE Received | [email protected] |