CVE-2026-16636 FluentSMTP <= 2.2.95 - Unauthenticated Stored Cross-Site Scripting via Recipient Display Name (to.name) in Email Logs
Unauthenticated attackers can inject scripts via recipient display names in email logs, potentially compromising administrator accounts.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-16636?
CVE-2026-16636 is a high-severity cross-site scripting vulnerability in wpmanageninja FluentSMTP – WP SMTP Plugin with Amazon SES, SendGrid, Mailgun, Postmark, Cloudflare, toSend, Gmail and Any SMTP, published on 6 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-16636?
How do I fix CVE-2026-16636?
No fix has been published for CVE-2026-16636 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-16636 being exploited?
There is no known exploitation of CVE-2026-16636 in the wild and no public exploit code.
Sources
Also known as GHSA-v4r4-2fwc-5qq5.