Time-of-check Time-of-use (TOCTOU) Race Condition

Overview github.com/mattermost/mattermost/server/channels/app is a private-cloud Slack alternative Affected versions of this package are vulnerable to Time-of-check Time-of-use TOCTOU Race Condition in the authentication process. An attacker can gain unauthorized access to multiple authenticated...

EUVD-2026-22915

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...

GHSA-MH4X-RMRX-3HP4 Mattermost has session spoofing due to lack of single-use consumption of guest magic link tokens enforcement

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...

Mattermost has session spoofing due to lack of single-use consumption of guest magic link tokens enforcement

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...

CVE-2026-3590

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...

CVE-2026-3590

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...

CVE-2026-3590 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...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. Vulnerabilities exist in Mattermost versions 10.11.12 and earlier of the 10.11.x series, as well as versions 11.5.0 and earlier of the 11.5.x series, 11.4.2 and earlier of the 11.4.x series, and 11.3...