What’s Vulnerable › Vulnerabilities
CVE-2026-75962: Post SMTP <= 4.0.1 - Unauthenticated Stored DOM-Based Cross-Site Scripting via 'user_email' Parameter (Multisite Registration → Failed Email Log)
- Severity: high (CVSS 7.2 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.3% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-10-06 · updated 2026-10-09
- Weakness: CWE-79
Description
The Post SMTP – Complete Email Deliverability and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'user_email' parameter in all versions up to, and including, 4.0.1 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. This is exploitable without authentication on WordPress Multisite installations with public registration enabled, as WordPress accepts email addresses containing numeric HTML character references that Post SMTP's stricter validator rejects, persisting the attacker-controlled address verbatim to the email log via the failed-send exception message.
Affected products
- saadiqbal Post SMTP – Complete Email Delivery and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App: through 4.0.1
References
- https://plugins.trac.wordpress.org/browser/post-smtp/tags/3.9.5/Postman/Postman-Email-Log/PostmanEmailLogService.php#L215
- https://plugins.trac.wordpress.org/browser/post-smtp/tags/3.9.5/Postman/Postman-Mail/PostmanEmailAddress.php#L63
- https://plugins.trac.wordpress.org/browser/post-smtp/tags/3.9.5/Postman/PostmanEmailLogs.php#L538
- https://plugins.trac.wordpress.org/browser/post-smtp/tags/3.9.5/Postman/PostmanWpMail.php#L374
- https://plugins.trac.wordpress.org/browser/post-smtp/tags/3.9.5/script/postman-email-logs.js#L711
- https://plugins.trac.wordpress.org/changeset/3711068/post-smtp/trunk/Postman/Postman-Email-Log/PostmanEmailLogService.php
- https://plugins.trac.wordpress.org/changeset?reponame=&new=3711079%40post-smtp%2Ftags%2F4.0.2&old=3664536%40post-smtp%2Ftags%2F4.0.1
- https://www.wordfence.com/threat-intel/vulnerabilities/id/accac3da-0318-4e79-a163-ed9ff2af692b?source=cve
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