CVE-2026-46349 | Mastodon is a free, open-source social network server based … | CVSS 5.3 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 attackers to re-arrange a valid signed JSON-LD activity from a third-party actor to have it processed differently. This vulnerability is fixed in 4.5.10, 4.4.17, and 4.3.23.

Metadata

CVE ID: CVE-2026-46349
State: PUBLISHED
Assigner: GitHub_M
Reserved: 2026-05-13 18:37 UTC
Published: 2026-06-24 19:40 UTC
Last updated: 2026-06-25 13:16 UTC
Primary CWE: CWE-347
CWE-347: Improper Verification of Cryptographic Signature
Vendor / Product: mastodon / mastodon
Sources: cve.org · NVD

Severity & Metrics

5.3 MEDIUM CVSS 3.1

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

SSVC — CISA Coordinator

Exploitation: none
Automatable: yes
Tech. Impact: partial

Affected products (1)

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

Weakness (CWE)

CWE	Source	Description
CWE-347	cna	CWE-347: Improper Verification of Cryptographic Signature

CVSS scores (1)

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

References (1)

https://github.com/mastodon/mastodon/security/advisories/GHSA-chgx-jx3p-rf73 https://github.com/mastodon/mastodon/security/advisories/GHSA-chgx-jx3p-rf73