Post SMTP: A security weakness
Post SMTP is affected by a security weakness. Exploitation requires at least subscriber-level access. The resulting impact depends on how the affected component exposes the vulnerable operation.
- Component
- Post SMTP
- Plugin slug
post-smtp- Affected
- See vendor advisory
- Safe version
- See mitigation notes
- Published
- Mar 18, 2026
- Weakness
- CWE-862 — Missing Authorization
This CVE was published Mar 18, 2026 and is one of 27 known issues for this plugin.
Update, patch or deactivate.
Update Post SMTP to a release outside the affected range, or disable and remove it until a fixed version is available.
No confirmed safe version is listed. Consider a vendor-supported patch or temporarily restricting the affected functionality while you assess the risk.
Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.
Technical 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.
CVE / CNA vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N