Input validation error in Mastodon - CVE-2024-25623
Published: February 17, 2024 / Updated: April 23, 2026
Vulnerability identifier: #VU126972
CSH Severity: Medium
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2024-25623
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to impersonate remote accounts.
The vulnerability exists due to improper input validation in FetchRemoteStatusService when fetching remote statuses. A remote user can upload a crafted Activity Streams document to a remote server and make a Mastodon server fetch it to impersonate remote accounts.
Exploitation requires a remote server that allows account registration, accepts arbitrary user-uploaded documents on the same domain as ActivityPub actors, and serves those documents in response to requests for Activity Streams media types.
Affected software
Mastodon
How to mitigate CVE-2024-25623
Install security update from vendor's website.
Mastodon - addressed in versions 3.5.19, 4.0.15, 4.1.15, 4.2.7