CVE-2025-12421
Account Takeover via Code Exchange Endpoint
CVSS Score
9.9
EPSS Score
0.0%
EPSS Percentile
0th
Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to to verify that the token used during the code exchange originates from the same authentication flow, which allows an authenticated user to perform account takeover via a specially crafted email address used when switching authentication methods and sending a request to the /users/login/sso/code-exchange endpoint. The vulnerability requires ExperimentalEnableAuthenticationTransfer to be enabled (default: enabled) and RequireEmailVerification to be disabled (default: disabled).
| CWE | CWE-303 |
| Vendor | mattermost |
| Product | mattermost |
| Published | Nov 27, 2025 |
| Last Updated | Feb 26, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
Mattermost / Mattermost
11.0.0 ≤ 11.0.2 10.12.0 ≤ 10.12.1 10.11.0 ≤ 10.11.4 10.5.0 ≤ 10.5.12
Credits
daw10