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CVE-2026-107587— Improper Certificate Validation in hMailServer

Quick assessment

Affected
Progressive Robot Ltd hMailServer
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.

渐进机器人（Progressive Robot）hMailServer 6.3.2 至 6.3.5 版本的 Web 邮件系统中存在证书验证不当的漏洞，允许远程未认证的攻击者实现如下攻击效果：攻击者发送给该账户的 S/MIME 加密邮件，在后续由该账户转发给其他通信方时，会被错误地使用攻击者的公钥进行加密。 当收件人打开一条已签名的邮件时，Web 邮件系统会保存该邮件签名者的证书，用于对回复邮件进行加密，而不论服务器是否验证通过该证书的信任链。系统在保存证书时，优先采用证书中列出的第一个电子邮件地址，而非邮件“Fro

CVSS 5.9 · Medium
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I. Basic Information for CVE-2026-107587

Vulnerability Information
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Vulnerability Title
Improper Certificate Validation in hMailServer
Source: CVE Program / CVE List V5
Vulnerability Description
Improper certificate validation in the webmail of Progressive Robot hMailServer 6.3.2 through 6.3.5 allows a remote unauthenticated attacker to have S/MIME-encrypted mail that the account later sends to another correspondent also encrypted to the attacker's key. When its recipient opened a signed message, the webmail kept the signer's certificate for encrypting replies whether or not the server found its chain trusted, under the first e-mail address the certificate listed rather than the message's From address, and beside any certificate already held for that address. Encrypted mail later sent from the webmail to that address was encrypted to every certificate held for it, so a holder of the kept certificate's key who obtains a copy of such a message can read it.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
证书验证不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Progressive Robot Ltd hMailServer 6.3.2 ~ 6.3.6 -

II. Public POCs for CVE-2026-107587

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III. Intelligence Information for CVE-2026-107587

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Patches & Fixes for CVE-2026-107587 (1)

Vendor Advisories for CVE-2026-107587 (1)

Same Patch Batch · Progressive Robot Ltd · 2026-10-08 · 24 CVEs total

CVE-2026-103647 8.0 HIGH Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in hM
CVE-2026-103010 7.8 HIGH Heap-based Buffer Overflow in hMailServer
CVE-2026-104660 7.8 HIGH Missing Authorization in hMailServer
CVE-2026-104658 7.8 HIGH Reliance on Untrusted Inputs in a Security Decision in hMailServer
CVE-2026-107573 7.8 HIGH Incorrect Default Permissions in hMailServer
CVE-2026-107576 7.5 HIGH Inefficient Algorithmic Complexity in hMailServer
CVE-2026-107577 7.5 HIGH Loop with Unreachable Exit Condition ('Infinite Loop') in hMailServer
CVE-2026-107574 7.5 HIGH Inefficient Algorithmic Complexity in hMailServer
CVE-2026-107579 7.5 HIGH Inefficient Algorithmic Complexity in hMailServer
CVE-2026-104659 7.5 HIGH Origin Validation Error in hMailServer
CVE-2026-103649 7.5 HIGH Synchronous Access of Remote Resource without Timeout in hMailServer
CVE-2026-107584 7.4 HIGH Not Failing Securely ('Failing Open') in hMailServer
CVE-2026-104704 7.4 HIGH Cleartext Transmission of Sensitive Information in hMailServer
CVE-2026-107578 6.7 MEDIUM Improper Link Resolution Before File Access ('Link Following') in hMailServer
CVE-2026-107583 6.5 MEDIUM Inefficient Algorithmic Complexity in hMailServer
CVE-2026-107572 6.5 MEDIUM Inefficient Regular Expression Complexity in hMailServer
CVE-2026-107581 6.5 MEDIUM Inefficient Algorithmic Complexity in hMailServer
CVE-2026-107582 6.5 MEDIUM Inefficient Algorithmic Complexity in hMailServer
CVE-2026-107580 6.5 MEDIUM Inefficient Algorithmic Complexity in hMailServer
CVE-2026-103011 6.5 MEDIUM Heap-based Buffer Overflow in hMailServer

Showing top 20 of 24 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: hMailServer
Same vendor: Progressive Robot Ltd
Same weakness: CWE-295

V. Comments for CVE-2026-107587

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