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

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Summary

CVECVE-2026-2559
StatePUBLISHED
AssignerWordfence
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-18 16:16:27 UTC
Updated2026-04-22 21:32:08 UTC
DescriptionThe 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.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

EPSS: 0.000340000 probability, percentile 0.100130000 (date 2026-04-22)

Problem Types: CWE-862 | CWE-862 CWE-862 Missing Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Saadiqbal Post SMTP Complete Email Deliverability And SMTP Solution With Email Logs Alerts Backup SMTP Mobile App affected 3.8.0 semver Not specified

References

ReferenceSourceLinkTags
www.wordfence.com/threat-intel/vulnerabilities/id/323436b5-fbfe-4923-8b08-93c1f... [email protected] www.wordfence.com
plugins.trac.wordpress.org/changeset/3484515 [email protected] plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/post-smtp/trunk/Postman/Wizard/NewWizard.php [email protected] plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/post-smtp/trunk/Postman/Wizard/NewWizard.php [email protected] plugins.trac.wordpress.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Michael Iden (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-02-15T19:21:39.000ZVendor Notified
CNA2026-03-17T00:00:00.000ZDisclosed
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