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CVE-2026-40016

Quick assessment

Affected
Open-Xchange GmbH OX Dovecot Pro
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.

Open-Xchange OX Dovecot Pro是德国Open-Xchange公司的一个邮件存储与投递系统。 Open-Xchange OX Dovecot Pro存在资源管理错误漏洞，该漏洞源于允许攻击者上传恶意Sieve脚本绕过配置的CPU时间限制，可能导致服务器性能下降。

CVSS 5.3 · Medium EPSS 0.43% · P35

Possible ATT&CK Techniques 1 AI

T1498 · Network Denial of Service

Affected Version Matrix 1

VendorProduct Version RangeStatus
Open-Xchange GmbH OX Dovecot Pro ≤ 2.3.0 affected
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I. Basic Information for CVE-2026-40016

Vulnerability Information
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Vulnerability Title
N/A
Source: CVE Program / CVE List V5
Vulnerability Description
Attacker can upload a malicious Sieve script over ManageSieve service (or locally) to bypass configured CPU time limits for Sieve up to 130 times of the configured limit. Attacker can use this to degrade server performance and bypass configured CPU time limits for Sieve scripts. Install fixed version, or alternatively prevent direct access to Sieve scripts via ManageSieve or local access. No publicly available exploits are known.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Vulnerability Title
Open-Xchange OX Dovecot Pro 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Open-Xchange OX Dovecot Pro是德国Open-Xchange公司的一个邮件存储与投递系统。 Open-Xchange OX Dovecot Pro存在资源管理错误漏洞，该漏洞源于允许攻击者上传恶意Sieve脚本绕过配置的CPU时间限制，可能导致服务器性能下降。
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
Open-Xchange GmbH OX Dovecot Pro 0 ~ 2.3.0 -

II. Public POCs for CVE-2026-40016

# POC Description Source Link Shenlong Link
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III. Intelligence Information for CVE-2026-40016

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Vendor Advisories for CVE-2026-40016 (1)

Same Patch Batch · Open-Xchange GmbH · 2026-05-12 · 5 CVEs total

CVE-2026-27851 7.4 HIGH Open-Xchange OX Dovecot Pro 安全漏洞
CVE-2026-33603 6.8 MEDIUM Open-Xchange OX Dovecot Pro 安全漏洞
CVE-2026-42006 4.3 MEDIUM Open-Xchange OX Dovecot Pro 资源管理错误漏洞
CVE-2026-40020 3.1 LOW Open-Xchange OX Dovecot Pro 访问控制错误漏洞

IV. Related Vulnerabilities

Same product: OX Dovecot Pro
Same vendor: Open-Xchange GmbH
Same weakness: CWE-400

V. Comments for CVE-2026-40016

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