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CVE-2026-2559— Post SMTP <= 3.8.0 - Missing Authorization to Authenticated (Subscriber+) Office 365 OAuth Configuration Overwrite

Quick assessment

Affected
saadiqbal Post SMTP – Complete Email Deliverability and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

WordPress和WordPress plugin都是WordPress基金会的产品。WordPress是一套使用PHP语言开发的博客平台。该平台具有在基于PHP和MySQL的服务器上架设个人博客网站的功能。WordPress plugin是一个应用插件。 WordPress plugin Post SMTP 3.8.0及之前版本存在安全漏洞，该漏洞源于handle_office365_oauth_redirect函数缺少能力检查，可能导致Office 365 OAuth邮件配置被覆盖。

CVSS 5.3 · Medium EPSS 0.34% · P25

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-2559

Vulnerability Information
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Vulnerability Title
Post SMTP <= 3.8.0 - Missing Authorization to Authenticated (Subscriber+) Office 365 OAuth Configuration Overwrite
Source: CVE Program / CVE List V5
Vulnerability Description
The Post SMTP plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the `handle_office365_oauth_redirect()` function in all versions up to, and including, 3.8.0. This is due to the function being hooked to `admin_init` without any `current_user_can()` check or nonce verification. This makes it possible for authenticated attackers, with Subscriber-level access and above, to overwrite the site's Office 365 OAuth mail configuration (access token, refresh token, and user email) via a crafted URL. The configuration option is used during wizard setup of Microsoft365 SMTP, only available in the Pro option of the plugin. This could cause an Administrator to believe an attacker-controlled Azure app is their own, and lead them to connect the plugin to the attacker's account during configuration after upgrading to Pro.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制缺失
Source: CVE Program / CVE List V5
Vulnerability Title
WordPress plugin Post SMTP 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
WordPress和WordPress plugin都是WordPress基金会的产品。WordPress是一套使用PHP语言开发的博客平台。该平台具有在基于PHP和MySQL的服务器上架设个人博客网站的功能。WordPress plugin是一个应用插件。 WordPress plugin Post SMTP 3.8.0及之前版本存在安全漏洞，该漏洞源于handle_office365_oauth_redirect函数缺少能力检查，可能导致Office 365 OAuth邮件配置被覆盖。
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
saadiqbal Post SMTP – Complete Email Deliverability and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App * ~ 3.8.0 -

II. Public POCs for CVE-2026-2559

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
default-local-qwen3.6 · 14877 chars
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III. Intelligence Information for CVE-2026-2559

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Patches & Fixes for CVE-2026-2559 (3)

Vendor Advisories for CVE-2026-2559 (1)

IV. Related Vulnerabilities

Same product: Post SMTP – Complete Email Deliverability and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App
Same vendor: saadiqbal
Same weakness: CWE-862

V. Comments for CVE-2026-2559

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