dbcve.org
Missing AuthorizationWeakness · CWE-862

CVE-2026-2559

MEDIUM · 5.3 CVSS v3.1 Published 2026-03-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
59/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The Post SMTP WordPress plugin has a Broken Access Control vulnerability in the handle_office365_oauth_redirect() function. This function is hooked to admin_init without any capability check (current_user_can) or nonce verification, allowing any authenticated user with Subscriber-level access or higher to manipulate Office 365 OAuth configuration settings (access token, refresh token, user email) via a crafted URL. An attacker can pre-configure malicious OAuth credentials that an administrator will unknowingly connect to during Pro plugin setup.

MitigationAdd a current_user_can() capability check and nonce verification to the handle_office365_oauth_redirect() function to ensure only authorized administrators can modify OAuth configuration.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify Post SMTP plugin is installed
    Navigate to WordPress admin dashboard > Plugins, or check the wp-content/plugins directory for the 'post-smtp' folder. Confirm the plugin is active.
    Affected if Post SMTP plugin is installed and active
  2. Locate the vulnerable function
    Access the WordPress site files via FTP or file manager. Navigate to wp-content/plugins/post-smtp/ and search for 'handle_office365_oauth_redirect' in the plugin files, typically in the main plugin file or an office365-related file.
    Affected if The function handle_office365_oauth_redirect() exists in the plugin code
  3. Verify no capability check exists
    Open the file containing handle_office365_oauth_redirect and examine the function. Look for absence of 'current_user_can' or similar WordPress capability checks before performing OAuth configuration actions.
    Affected if No current_user_can() check is present in the handle_office365_oauth_redirect function
  4. Confirm admin_init hook usage
    Search the plugin files for 'admin_init' hook connected to handle_office365_oauth_redirect. Use grep or text search in the plugin directory.
    Affected if The function is hooked to admin_init without additional authorization checks
  5. Check for nonce verification
    Examine the handle_offile365_oauth_redirect function for wp_verify_nonce or check_admin_referer calls. Verify no nonce token validation is performed.
    Affected if No nonce verification (wp_verify_nonce or check_admin_referer) is present in the function
  6. Assess WordPress user configuration
    In WordPress admin, go to Users > All Users. Check if any users with Subscriber role exist, or if the site allows user registration that creates Subscriber-level accounts.
    Affected if The site has user accounts with Subscriber-level access or allows public registration to Subscriber role

A user is affected if the Post SMTP plugin is installed with the handle_office365_oauth_redirect function hooked to admin_init without current_user_can capability checks or nonce verification, and the site has any authenticated users with Subscriber-level access or higher.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Add a current_user_can() capability check and nonce verification to the handle_office365_oauth_redirect() function to ensure only authorized administrators can modify OAuth configuration.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,570
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-2559 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data