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CVE-2026-84458— Zammad: Account takeover via unverified email matching during SSO auto-link

Quick assessment

Affected
zammad zammad
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.

Zammad 是一款基于 Web 的开源帮助台/客户支持系统。在版本 7.1.2 之前，当启用“初始登录时自动关联账户”（Automatic account link on initial logon）设置时，Zammad 会将来自第三方（SSO）的身份绑定到已有的本地账户，其匹配依据是身份提供者（Identity Provider）报告的电子邮件地址，但未验证该提供者是否实际确认了对该电子邮件的所有权。攻击者只要控制了任一已配置身份提供者上的任何身份（默认情况下，包括 Zammad 通过多租户 Microsoft

CVSS 9.1 · Critical EPSS 0.36% · P27
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I. Basic Information for CVE-2026-84458

Vulnerability Information
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Vulnerability Title
Zammad: Account takeover via unverified email matching during SSO auto-link
Source: CVE Program / CVE List V5
Vulnerability Description
Zammad is a web based open source helpdesk/customer support system. Prior to 7.1.2, when the "Automatic account link on initial logon" setting is enabled, Zammad binds an incoming third-party (SSO) identity to an existing local account by matching the email address the identity provider reports, without verifying that the provider actually confirmed ownership of that email. An attacker who controls any identity at a configured provider, including, by default, any Azure AD tenant via Zammad's multi-tenant Microsoft 365 /common app registration, can set that identity's email to a victim's address, authenticate, and be logged in as the victim. This bypasses the victim's local password entirely and affects any existing account, including agents and administrators. Zammad will honor the xms_edov ID token claim when email verification is required in the Microsoft 365 setting, treating a missing claim as unverified. This issue is fixed in version 7.1.2.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
认证机制不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
zammad zammad < 7.1.2 -

II. Public POCs for CVE-2026-84458

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III. Intelligence Information for CVE-2026-84458

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Other References for CVE-2026-84458 (2)

Same Patch Batch · zammad · 2026-09-25 · 30 CVEs total

CVE-2026-61525 8.8 HIGH Zammad: Arbitrary File Deletion via Unvalidated Session Identifier in Long Polling Control
CVE-2026-56733 8.7 HIGH Zammad: Incorrect Authorization and Improper Privilege Management
CVE-2026-56725 8.7 HIGH Zammad: Denial of Service via OTRS Import Controller
CVE-2026-84462 8.6 HIGH Zammad: AI Agent template sanitizer bypass leads to remote code execution
CVE-2026-56731 8.4 HIGH Zammad: Cross-Site Scripting in Ticket Notifications
CVE-2026-56724 7.1 HIGH Zammad: Incorrect implementation of permission checks in the knowledge base module
CVE-2026-56723 7.1 HIGH Zammad: Missing authorization on ticket attachment download
CVE-2026-84465 7.1 HIGH Zammad: S/MIME signature verification allows forged sender impersonation
CVE-2026-56727 7.1 HIGH Zammad: PGP signature spoofing via unvalidated verification return
CVE-2026-84464 7.1 HIGH Zammad: IDOR in External Data Source rendering exposes ticket, user, group, and organizati
CVE-2026-84461 6.9 MEDIUM Zammad: Missing rate limiting allows password brute-forcing during two-factor login
CVE-2026-63207 6.9 MEDIUM Zammad: Sensitive Information Exposure in Integration Administration API
CVE-2026-84463 6.3 MEDIUM Zammad: Stored HTML injection in Knowledge Base video widget enables forced session switch
CVE-2026-84460 5.3 MEDIUM Zammad: Missing Authorization in TagsController#list Allows Cross-Object Tag Enumeration
CVE-2026-56728 5.3 MEDIUM Zammad: Cross-User Taskbar Item Access Control Vulnerability
CVE-2026-56735 5.3 MEDIUM Zammad: Improper neutralization of `srcset` attribute in IMG tags in Zammad
CVE-2026-56734 5.3 MEDIUM Zammad: Avatar Image URL Server-Side Request Forwarding
CVE-2026-56732 5.3 MEDIUM Zammad: Malicious input in Ticket Body Enables Session Termination
CVE-2026-63206 5.3 MEDIUM Zammad: Remote image tracking bypass via shortened URL scheme
CVE-2026-61855 5.3 MEDIUM Zammad: Invalid PGP Detached Signatures Reported as Good Signature on Inbound Mail

Showing top 20 of 30 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: zammad
Same vendor: zammad
Same weakness: CWE-287

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