Post SMTP <= 3.8.0 — Missing Authorization to Authenticated (Subscriber+) Office 365 OAuth Configuration Overwrite
CVE-2026-2559Published · Updated Action summary
Affected: ≤3.8.0Update to 3.9.0 or newer
All remediation steps- Severity
- Medium5.3
- CVSS
- 5.3CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:NWhat does this vector mean?
AV:NAttack vector- Network
AC:HAttack complexity- High
PR:LPrivileges required- Low
UI:NUser interaction- None
S:UScope- Unchanged
C:NConfidentiality- None
I:HIntegrity- High
A:NAvailability- None
- Weakness
- CWE-862 Missing Authorization
- Required access
- Unknown
- Exploit prediction (EPSS)
- No score
- CISA KEV
- Not listed
On this page8
Am I affected?
- Affected≤ 3.8.0
- Patched in3.9.0
Update to 3.9.0 or newer.
You are affected if you run ≤ 3.8.0. Version 3.9.0 and later are not affected by this issue.
- Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under Post SMTP – Complete Email Delivery and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App.
- No admin access? Run a passive check of your site. It reads public files only.
What to do
- Update to version 3.9.0, or a newer patched version
- Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
- Watch Post SMTP – Complete Email Delivery and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App to get an email when the next vulnerability is published.
Advisory
Source description from Wordfence Intelligence, credited to Michael Iden (Mickhat).
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.
Exploits & references
Proof-of-concept & detection
No public proof-of-concept or detection template is known for this vulnerability.
Advisories & patches
- Advisorywordfence.com
Related CVEs
More in Post SMTP – Complete Email Delivery and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App
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| High7.2 | Unauthenticated Stored Cross-Site Scripting ≤3.6.2Update to 3.6.3 | CVE-2026-48838 | |
| Medium6.1 | Reflected DOM-Based Cross-Site Scripting via url Parameter ≤5.5.8Update to 5.5.9 | CVE-2024-13362 | |
| High7.2 | Unauthenticated Stored Cross-Site Scripting via 'event_type' ≤3.8.0Update to 3.9.0 | CVE-2026-3090 |
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≤3.8.0Update to 3.9.0
Same weakness (Missing Authorization)
All Missing Authorization| Severity | Vulnerability | CVE | Published |
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| Critical9.8 | Unauthenticated PHP Object Injection to Remote Code Execution via 'form' Parameter | CVE-2026-119077 | |
| Medium5.3 | Unauthenticated Sensitive Information Exposure in 'search' Parameter | CVE-2026-121518 |
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Timeline
CVE published
Severity medium, CVSS 5.3
Record last updated
Sources & licenses
Wordfence record- Vulnerability data
- Wordfence Intelligence. [object Object] Licensed under the CC BY-SA 4.0.
- CVE® identifiers
- [object Object]. Used under the CVE Program. CVE® is a registered trademark of The MITRE Corporation.
- CVSS / CWE
- National Vulnerability Database (NVD), shown unmodified. This product uses the NVD API but is not endorsed or certified by the NVD.
- VulnCrest content
- Summary, remediation guidance and page layout © VulnCrest. Not sourced from NVD.