Improper Authentication in Mastodon - #VU147214
Published: September 7, 2026
Vulnerability identifier: #VU147214
CSH Severity: Medium
CVSS v4: 9.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-287
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to log in to affected accounts without a valid password.
The vulnerability exists due to improper authentication in Mastodon\'s authentication flow when processing sign-in attempts for accounts without database-stored passwords. A remote attacker can provide any password and proceed to second-factor authentication to log in to affected accounts without a valid password.
Exploitation requires a valid security key, backup code, or TOTP token for an account with two-factor authentication enabled that uses LDAP, PAM, or server-configured SSO.
Affected software
Mastodon
Remediation
Install security update from vendor's website.
Mastodon - addressed in versions 4.4.24, 4.5.17, 4.6.7, 4.7.1