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Vulnerability record · CVE-2026-16636 · published 6 August 2026

CVE-2026-16636: Cross-site scripting vulnerability

The FluentSMTP – WP SMTP Plugin with Amazon SES, SendGrid, MailGun, Postmark, Google and Any SMTP Provider plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Recipient Display Name (to.name) in Email Logs in all versions up to, and including, 2.2.95 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The payload is delivered via an attacker-controlled recipient display name (to.name) in a wp_mail() call and does not fire in the log list view — only in the detail view when an administrator uses the Prev/Next navigation controls, as that path bypasses the escapeHtml pipeline used by the list view.

7.2 CVSS 3.1 High EPSS 0.53% · top 57.4% CWE-79 · Cross-site scripting Deferred
7.2CVSS 3.1 base score
0.53%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
9References
12 Aug 2026Last modified by NVD

Description

The FluentSMTP – WP SMTP Plugin with Amazon SES, SendGrid, MailGun, Postmark, Google and Any SMTP Provider plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Recipient Display Name (to.name) in Email Logs in all versions up to, and including, 2.2.95 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The payload is delivered via an attacker-controlled recipient display name (to.name) in a wp_mail() call and does not fire in the log list view — only in the detail view when an administrator uses the Prev/Next navigation controls, as that path bypasses the escapeHtml pipeline used by the list view.

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

References

LinkTags
https://plugins.trac.wordpress.org/browser/fluent-smtp/tags/2.2.95/app/Models/Logger.php#L165
https://plugins.trac.wordpress.org/browser/fluent-smtp/tags/2.2.95/app/Models/Logger.php#L310
https://plugins.trac.wordpress.org/browser/fluent-smtp/tags/2.2.95/app/Services/Mailer/BaseHandler.php#L290
https://plugins.trac.wordpress.org/browser/fluent-smtp/tags/2.2.95/app/Services/Mailer/BaseHandler.php#L357
https://plugins.trac.wordpress.org/browser/fluent-smtp/tags/2.2.95/assets/admin/js/fluent-mail-admin-app.js
https://plugins.trac.wordpress.org/changeset/3635135/fluent-smtp/trunk/assets/admin/js/fluent-mail-admin-app.js
https://plugins.trac.wordpress.org/changeset?old_path=%2Ffluent-smtp/tags/2.2.95&new_path=%2Ffluent-smtp/tags/2.3.0
https://plugins.trac.wordpress.org/changeset?reponame=&new=3635135%40fluent-smtp%2Ftags%2F2.3.0&old=3428610%40fluent-smt
https://www.wordfence.com/threat-intel/vulnerabilities/id/4ad3ed6b-19d4-47c7-a56c-54092c767fe9?source=cve

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Source: NIST National Vulnerability Database (record CVE-2026-16636), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.