CVE-2026-16636
Received Received - Intake

Stored XSS in FluentSMTP WordPress Plugin via Email Logs

Publication date: 2026-08-06

Last updated on: 2026-08-06

Assigner: Wordfence

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.

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Meta Information

Published
2026-08-06
Last Modified
2026-08-06
Generated
2026-08-06
AI Q&A
2026-08-06
EPSS Evaluated
N/A
NVD
CVE-2026-16636
EUVD
EUVD-2026-53702

Affected Vendors & Products

Currently, no data is known.

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

This vulnerability is a Stored Cross-Site Scripting (XSS) flaw in the FluentSMTP WordPress plugin. It allows unauthenticated attackers to inject malicious scripts via the recipient display name in email logs. The scripts execute when an administrator views the log details using Prev/Next navigation, bypassing input sanitization in that view.

Detection Guidance

Check WordPress email logs for suspicious recipient display names containing scripts. Inspect plugin versions and update FluentSMTP to 2.2.96 or later. Review admin navigation controls in email log detail views for unexpected script execution.

Impact Analysis

An attacker could steal sensitive data like session cookies or login credentials by tricking an admin into viewing a crafted log entry. They might also perform actions on behalf of the admin or deface the WordPress site. The attack requires no authentication and targets administrators viewing logs.

Compliance Impact

This vulnerability could lead to unauthorized access to personal data, violating GDPR and HIPAA requirements for data protection. If exploited, it may result in data breaches, triggering mandatory breach notifications and potential fines under these regulations.

Mitigation Strategies

Update the FluentSMTP plugin to version 2.2.96 or higher immediately. Disable email log detail view navigation if possible. Monitor for unauthorized script execution in admin interfaces.

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