CVE-2026-48028 | Mastodon is a free, open-source social network server based … | CVSS 6.5 MEDIUM

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.

Metadata

CVE ID: CVE-2026-48028
State: PUBLISHED
Assigner: GitHub_M
Reserved: 2026-05-20 17:44 UTC
Published: 2026-06-24 19:43 UTC
Last updated: 2026-06-24 19:43 UTC
Primary CWE: CWE-354
CWE-354: Improper Validation of Integrity Check Value
Vendor / Product: mastodon / mastodon
Sources: cve.org · NVD

Severity & Metrics

6.5 MEDIUM CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Affected products (1)

Vendor	Product	Platform	Versions
mastodon	mastodon	—	>= 4.5.0-beta.1, < 4.5.10, >= 4.4.0-beta.1, < 4.4.17, < 4.3.23

Weakness (CWE)

CWE	Source	Description
CWE-354	cna	CWE-354: Improper Validation of Integrity Check Value

CVSS scores (1)

Score	Severity	Version	Source	Vector
6.5	MEDIUM	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

References (1)

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