CVE-2026-48028 — MEDIUM (6.5)

Vulnerability 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.

CVSS Score

6.5

MEDIUM

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

Related Weaknesses (CWE)

CWE-354

References

https://github.com/mastodon/mastodon/security/advisories/GHSA-53m7-2wrh-q839

FAQ

What is CVE-2026-48028?

CVE-2026-48028 is a vulnerability with a CVSS score of 6.5 (MEDIUM). 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...

How severe is CVE-2026-48028?

CVE-2026-48028 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-48028?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.