Race Condition in Guest Magic Link Authentication Allows Token Reuse
Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 11.4.x <= 11.4.2, 11.3.x <= 11.3.2 fail to enforce atomic single-use consumption of guest magic link tokens, which allows an attacker with access to a valid magic link to establish multiple independent authenticated sessions via concurrent requests.. Mattermost Advisory ID: MMSA-2026-00624
Problem Types
| Type | CWE ID | Description |
|---|
| CWE | CWE-367 | CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition |
Type: CWE
Description: CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition
Metrics
| Version | Base score | Base severity | Vector |
|---|
| 3.1 | 6.5 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N |
Version: 3.1
Base score: 6.5
Base severity: MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N