CVE-2026-1661

Mail Logging <= 1.16.0 - Cross-Site Scripting to Unauthenticated Arbitrary HTML Content Injection in Admin Log

2026-09-28 00:00
Kasia Sok

Strategic Overview

Status
Patched in 1.17.0
Affected Plugin
WP Mail Logging
Affected Version
<= 1.16.0
CVSS
4.7Medium
Weakness type
CWE-20 · Improper Input Validation
CVE
CVE-2026-1661
View all WP Mail Logging vulnerabilities

At a glance

CVE-2026-1661 is a medium-severity Improper Input Validation vulnerability in the WP Mail Logging WordPress plugin, affecting versions <= 1.16.0. It carries a CVSS score of 4.7 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 1.17.0; sites on affected versions should update now. Disclosed September 2026, reported by Kasia Sok.

Vulnerability Overview

The Mail Logging plugin for WordPress is vulnerable to HTML Injection in all versions up to, and including, 1.16.0. This is due to insufficient sanitization of logged email message content before rendering in admin screens, specifically missing removal of style blocks and navigation attributes from untrusted HTML. This makes it possible for unauthenticated attackers to inject arbitrary HTML content, including styled elements and navigation links, into admin email log screens via publicly accessible forms, deceiving administrators and redirecting their browsers to attacker-controlled pages.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site.

CWE-20: Improper Input Validation

Reaching this weakness in WP Mail Logging <= 1.16.0 takes no account at all. Improper input validation means the application accepts input without confirming it has the form, type or range the code downstream assumes.

The concrete impact depends on where the unvalidated value lands, which is why records in this class range from cosmetic bugs to full compromise. For WP Mail Logging the fix is 1.17.0: builds <= 1.16.0 are affected, anything from 1.17.0 onward is not.

Remediation

Update to version 1.17.0, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: WP Mail Logging 1.17.0 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Login Security
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-1661https://www.wordfence.com/threat-intel/vulnerabilities/id/77eabbd2-f682-4ff7-a411-c869b78a7a9bhttps://nvd.nist.gov/vuln/detail/CVE-2026-1661

Related records

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