CVE-2026-84465— Zammad: S/MIME signature verification allows forged sender impersonation
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 7.1.2 版本之前，当 Zammad 检查传入的 S/MIME 签名电子邮件的数字签名时，它并未验证签名证书是否真正可信，而仅检查系统中是否已存储一个名称匹配的证书。攻击者可以使用已真实可信发送者的名称创建自己的证书，并利用该证书发送伪造的电子邮件。Zammad 会显示该邮件带有与真实发送者发出的消息相同的“有效签名”指示，即使攻击者从未访问过该发送者的实际证书或私钥。该问题已在 7.1.2 版本中得到修复。
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I. Basic Information for CVE-2026-84465
Vulnerability Information
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Vulnerability Title
Zammad: S/MIME signature verification allows forged sender impersonation
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 Zammad checks the digital signature on an incoming S/MIME-signed email, it does not verify that the signing certificate is genuinely trusted, it only checks whether a certificate with a matching name is already stored in the system. An attacker can create their own certificate using the name of a real, previously trusted sender and use it to send a forged email. Zammad will display that email with the same "validly signed" indicator as a genuine message from the real sender, even though the attacker never had access to that sender's actual certificate or private key. 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:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用欺骗进行的认证绕过
Source: CVE Program / CVE List V5
Affected Products
II. Public POCs for CVE-2026-84465
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POC
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Other References for CVE-2026-84465 (2)
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https://github.com/zammad/zammad/security/advisories/GHSA-m9ff-hjr3-93h4 x_refsource_CONFIRM
Same Patch Batch · zammad · 2026-09-25 · 30 CVEs total
| CVE-2026-84458 | 9.1 CRITICAL | Zammad: Account takeover via unverified email matching during SSO auto-link |
| 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-2026-84464 | 7.1 HIGH | Zammad: IDOR in External Data Source rendering exposes ticket, user, group, and organizati |
| CVE-2026-56727 | 7.1 HIGH | Zammad: PGP signature spoofing via unvalidated verification return |
| CVE-2026-56723 | 7.1 HIGH | Zammad: Missing authorization on ticket attachment download |
| CVE-2026-63207 | 6.9 MEDIUM | Zammad: Sensitive Information Exposure in Integration Administration API |
| CVE-2026-84461 | 6.9 MEDIUM | Zammad: Missing rate limiting allows password brute-forcing during two-factor login |
| CVE-2026-84463 | 6.3 MEDIUM | Zammad: Stored HTML injection in Knowledge Base video widget enables forced session switch |
| CVE-2026-56735 | 5.3 MEDIUM | Zammad: Improper neutralization of `srcset` attribute in IMG tags in Zammad |
| CVE-2026-56728 | 5.3 MEDIUM | Zammad: Cross-User Taskbar Item Access Control Vulnerability |
| CVE-2026-56732 | 5.3 MEDIUM | Zammad: Malicious input in Ticket Body Enables Session Termination |
| CVE-2026-56734 | 5.3 MEDIUM | Zammad: Avatar Image URL Server-Side Request Forwarding |
| CVE-2026-84460 | 5.3 MEDIUM | Zammad: Missing Authorization in TagsController#list Allows Cross-Object Tag Enumeration |
| 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 → →
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