Vulnerability · CVE-2026-2559
The Post SMTP plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the function in all versions up to, and incl…
Published Mar 18, 2026 · corrected/updated Jun 17, 2026 · evidence confidence high
The Post SMTP plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the function in all versions up to, and including, 3.8.0. This is due to the function being hooked to without any 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.
Grounded briefings
Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.
Executive
CVE-2026-2559 is a medium public vulnerability record for this product. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.
System administrator
Identify whether this product is in your estate, then compare installed versions with the affected ranges. Affected version ranges have not been ingested yet. Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.
Security analyst
Signals on file: CVSS 5.3, EPSS 0.4%. It is not currently listed in the CISA Known Exploited catalog. Weakness classes: CWE-862. Sources contributing to this record: cve_org, epss, nvd. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.
Exploitation and remediation
Exploitation evidence
Not listed as known exploited in CISA KEV. Not in CISA KEV or VulnCheck KEV.
Patch and remediation
No required-action text is stored yet. Use the vendor or CERT links in Sources for patch availability.
Safe detection guidance
Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.
Technology hubs
Code
The project this record applies to. Exploit listings stay in References.
Timeline
Detection, updates, and resolution for this record.
Mar 18, 2026 · NIST NVD
Detected
The Post SMTP plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the function in all versions up to, and including, 3.8.0. This is due to the function being hooked to without any 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 m
Jun 17, 2026 · NIST NVD
Updated
The Post SMTP plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the function in all versions up to, and including, 3.8.0. This is due to the function being hooked to without any 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 m
Sources
- CVE.orgVulnerability recordCVE-2026-2559
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2026-2559
30-day exploitation probability 0.4%
first.org - NIST NVDVulnerability recordCVE-2026-2559
The Post SMTP plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the function in all versions up to, and including, 3.8.0. This is due to the function being hooked to withou
nvd.nist.gov