Description
MAS (Matrix Authentication Service) is a user management and authentication service for Matrix homeservers, written and maintained by Element. A logic flaw in matrix-authentication-service 0.20.0 through 1.4.0 allows an attacker with access to an authenticated MAS session to perform sensitive operations without entering the current password. These include changing the current password, adding or removing an e-mail address and deactivating the account. The vulnerability only affects instances which have the local password database feature enabled (passwords section in the config). Patched in matrix-authentication-service 1.4.1.
References2
Metrics
- CVSS 3.1
-
8.3
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H - EPSS — exploit probability
- 0% percentile: 40 · as of 9 November 2026
- CWE
- CWE-620
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.