CVE-2026-73379: Contact Form Supsystic Auth Bypass Flaw

CVE-2026-73379 Overview

CVE-2026-73379 is an authentication bypass vulnerability affecting the Contact Form by Supsystic WordPress plugin in versions prior to 1.10.0. The flaw is categorized under CWE-288 (Authentication Bypass Using an Alternate Path or Channel). Remote attackers can exploit the weakness over the network without authentication or user interaction. Successful exploitation results in limited impact to confidentiality and integrity, with no direct impact on availability. The vulnerability was published to the National Vulnerability Database (NVD) on August 18, 2026, and referenced through a Patchstack advisory.

Critical Impact
Unauthenticated network-based attackers can bypass authentication controls in Contact Form by Supsystic versions before 1.10.0, exposing limited confidentiality and integrity of the affected WordPress site.

Affected Products

Contact Form by Supsystic WordPress plugin, versions prior to 1.10.0
WordPress sites running the vulnerable plugin release
Web hosting environments with the plugin enabled and network-accessible

Discovery Timeline

2026-08-18 - CVE-2026-73379 published to NVD
2026-08-20 - Last updated in NVD database

Technical Details for CVE-2026-73379

Vulnerability Analysis

CVE-2026-73379 is an unauthenticated bypass vulnerability in the Contact Form by Supsystic WordPress plugin. The flaw maps to CWE-288, which describes authentication bypass using an alternate path or channel. Attackers reach protected plugin functionality without providing valid credentials by using a code path that skips the intended authentication check.

The vulnerability is network-exploitable and requires no privileges or user interaction. According to EPSS data dated 2026-08-21, the vulnerability carries a probability score of 0.21% and a percentile of 11.588, indicating low observed exploitation likelihood in the near term. Patchstack tracks the issue in its vulnerability database and confirms remediation in plugin version 1.10.0.

Root Cause

The root cause is missing or incorrectly enforced authentication in one or more plugin request handlers. The affected code path accepts requests without validating the caller's identity, allowing remote actors to invoke functionality intended for authenticated users. Specific handler names and internal routing details are not disclosed in the public advisory.

Attack Vector

An attacker sends crafted HTTP requests to the WordPress site that reach the plugin's vulnerable endpoint. Because the endpoint lacks proper authentication enforcement, the server processes the request as if it originated from a permitted user. No credentials, session tokens, or user interaction are required. See the Patchstack Vulnerability Advisory for advisory details.

Detection Methods for CVE-2026-73379

Indicators of Compromise

Unauthenticated HTTP requests to Contact Form by Supsystic plugin endpoints under /wp-admin/admin-ajax.php or /wp-json/ paths referencing the plugin
Plugin actions executed without a corresponding authenticated WordPress session cookie
Unexpected changes to plugin settings, forms, or submitted-data exports on sites still running versions below 1.10.0

Detection Strategies

Inventory WordPress installations and identify sites running Contact Form by Supsystic versions prior to 1.10.0
Review web server access logs for anomalous request patterns targeting plugin AJAX or REST endpoints from a single source IP
Correlate WordPress audit logs with web server logs to identify plugin operations that lack an associated authenticated user

Monitoring Recommendations

Forward WordPress and web server logs to a centralized logging pipeline for retention and query
Alert on high-volume or scripted requests to plugin endpoints originating from external IP addresses
Track plugin version drift across managed WordPress fleets and surface hosts still running versions below 1.10.0

How to Mitigate CVE-2026-73379

Immediate Actions Required

Upgrade Contact Form by Supsystic to version 1.10.0 or later on all affected WordPress sites
Audit recent plugin activity for unauthorized configuration changes or exported form submission data
Rotate any credentials or API keys that may have been exposed through plugin functionality

Patch Information

The vendor addressed CVE-2026-73379 in Contact Form by Supsystic version 1.10.0. Site administrators should update the plugin through the WordPress admin dashboard or via automated update tooling. Refer to the Patchstack Vulnerability Advisory for the authoritative fixed-version reference.

Workarounds

Deactivate and remove the Contact Form by Supsystic plugin until it can be updated to version 1.10.0 or later
Restrict access to WordPress admin and AJAX endpoints using a web application firewall (WAF) rule that filters unauthenticated requests to plugin actions
Limit administrative endpoint exposure by IP allow-listing where operationally feasible

bash

# Configuration example
# Update the plugin using WP-CLI on affected WordPress hosts
wp plugin update contact-form-by-supsystic --version=1.10.0
wp plugin get contact-form-by-supsystic --field=version