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CVE-2026-3590— Race Condition in Guest Magic Link Authentication Allows Token Reuse

Quick assessment

Affected
Mattermost Mattermost
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Mattermost是美国Mattermost公司的一个开源协作平台。 Mattermost 10.11.12及之前的10.11.x版本、11.5.0及之前的11.5.x版本、11.4.2及之前的11.4.x版本和11.3.2及之前的11.3.x版本存在安全漏洞，该漏洞源于未强制实施访客魔法链接令牌的原子单次使用，可能导致攻击者建立多个独立的经过身份验证的会话。

CVSS 6.5 · Medium EPSS 0.22% · P12

Possible ATT&CK Techniques 1 AI

T1133 · External Remote Services
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I. Basic Information for CVE-2026-3590

Vulnerability Information
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Vulnerability Title
Race Condition in Guest Magic Link Authentication Allows Token Reuse
Source: CVE Program / CVE List V5
Vulnerability Description
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
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
检查时间与使用时间(TOCTOU)的竞争条件
Source: CVE Program / CVE List V5
Vulnerability Title
Mattermost 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Mattermost是美国Mattermost公司的一个开源协作平台。 Mattermost 10.11.12及之前的10.11.x版本、11.5.0及之前的11.5.x版本、11.4.2及之前的11.4.x版本和11.3.2及之前的11.3.x版本存在安全漏洞，该漏洞源于未强制实施访客魔法链接令牌的原子单次使用，可能导致攻击者建立多个独立的经过身份验证的会话。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Mattermost Mattermost 10.11.0 ~ 10.11.12 -

II. Public POCs for CVE-2026-3590

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III. Intelligence Information for CVE-2026-3590

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Same Patch Batch · Mattermost · 2026-04-15 · 3 CVEs total

CVE-2026-28741 6.8 MEDIUM CSRF Protection Bypass Allows Updating a User's Authentication Method
CVE-2026-27769 2.7 LOW Connected Workspaces: Malicious remote server can manipulate arbitrary user's status

IV. Related Vulnerabilities

Same product: Mattermost
Same vendor: Mattermost
Same weakness: CWE-367

V. Comments for CVE-2026-3590

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