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CVE-2026-40205

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.

如果一个攻击者持有一个仅授予部分所需作用域（scopes）的 OAuth2 令牌，该攻击者仍可能成功认证。原因是，当配置中需要多个作用域时，远程令牌验证路径会接受仅包含其中一个作用域的令牌，而本地令牌验证路径则正确要求令牌必须包含所有所需作用域。因此，配置的授权策略未被强制执行，导致仅被授予部分所需权限的令牌在应当被拒绝的情况下被接受了。建议在令牌可以本地验证的场景下，使用本地令牌验证机制。请升级至不受漏洞影响的版本。目前尚未发现公开可用的利用方式。

CVSS 5.9 · Medium

Possible ATT&CK Techniques 1 AI

T1550.001 · Application Access Token
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I. Basic Information for CVE-2026-40205

Vulnerability Information
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Vulnerability Title
N/A
Source: CVE Program / CVE List V5
Vulnerability Description
An attacker that holds an OAuth2 token granting only part of the required scopes can authenticate, because when more than one scope is required in the configuration, the remote token validation paths accept a token that carries only one of them, while the local token validation path correctly requires all of them. The configured authorization policy is not enforced, so a token that was granted only part of the required permissions is accepted where it should have been rejected. Use local token validation where tokens can be validated locally. Update to non-vulnerable version. 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:L/I:H/A: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
Open-Xchange GmbH OX Dovecot Pro 2.3.11.2 ~ 2.3.22.2 -
Open-Xchange GmbH OX Dovecot CE 2.3.11.2 ~ 2.4.5 -

II. Public POCs for CVE-2026-40205

# POC Description Source Link Shenlong Link
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III. Intelligence Information for CVE-2026-40205

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Same Patch Batch · Open-Xchange GmbH · 2026-08-28 · 25 CVEs total

CVE-2026-42007 9.1 CRITICAL OpenWebmail 6.0 及之前版本 内存越界写漏洞
CVE-2026-42391 7.5 HIGH IMAP未认证ID命令引发内存与CPU资源耗尽
CVE-2026-27852 7.5 HIGH Dovecot 特定版本 IMAP 邮件解析内存耗尽 DoS
CVE-2026-33605 7.5 HIGH ManageSieve 认证前畸形命令崩溃DoS漏洞
CVE-2026-40018 7.4 HIGH 未知软件：无已知公开利用
CVE-2026-73208 7.4 HIGH Dovecot OAuth2 audience 冒充 scope 导致越权
CVE-2026-52687 6.5 MEDIUM Dovecot IMAP压缩算法致拒绝服务
CVE-2026-40014 6.5 MEDIUM IMAP THREAD命令致高CPU占用，修复指定版本
CVE-2026-40017 6.5 MEDIUM Dovecot特定版本IMAP THREAD命令哈希碰撞DoS漏洞
CVE-2026-73209 6.5 MEDIUM IMAP服务栈溢出拒绝服务漏洞
CVE-2026-33604 5.9 MEDIUM Dovecot SMTP邮件走私漏洞
CVE-2026-40019 5.9 MEDIUM ManageSieve 0.6.1 存在 CPU 耗尽型拒绝服务漏洞
CVE-2026-33606 4.8 MEDIUM Dovecot dsync流协议邮件内容注入漏洞
CVE-2026-42008 4.3 MEDIUM Dovecot 受信代理认证字段注入漏洞
CVE-2026-33607 4.3 MEDIUM IMAP LIST命令致CPU耗尽或DoS
CVE-2026-33263 4.3 MEDIUM 提交登录模块崩溃：高并发下连接上限触发 epoll 异常
CVE-2026-40015 4.3 MEDIUM IMAP-hibernate越界读致进程崩溃
CVE-2026-40013 4.3 MEDIUM ManageSieve 越界写导致拒绝服务漏洞
CVE-2026-42392 4.3 MEDIUM 该漏洞影响某软件的IMAP URLAUTH功能，版本未知，类型为信息泄露
CVE-2026-42395 4.3 MEDIUM OpenSSH可信代理NUL字节致登录进程崩溃

Showing top 20 of 25 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: OX Dovecot Pro
Same vendor: Open-Xchange GmbH
Same weakness: CWE-287

V. Comments for CVE-2026-40205

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