CVE-2026-40798: wpForo Forum SQL Injection Vulnerability

CVE-2026-40798 Overview

CVE-2026-40798 is an unauthenticated SQL injection vulnerability affecting the wpForo Forum plugin for WordPress in versions 3.0.4 and earlier. The flaw maps to CWE-89, Improper Neutralization of Special Elements used in an SQL Command. Remote attackers can exploit the issue over the network without authentication or user interaction, making any WordPress site running a vulnerable wpForo installation a viable target. The vulnerability was disclosed through Patchstack's WordPress vulnerability database.

Critical Impact
Unauthenticated attackers can inject SQL statements into the wpForo Forum plugin, exposing forum and WordPress database contents and enabling further compromise of affected sites.

Affected Products

wpForo Forum plugin for WordPress, all versions <= 3.0.4
WordPress sites with wpForo installed and network-reachable forum endpoints
Any deployment exposing the vulnerable plugin to unauthenticated HTTP requests

Discovery Timeline

2026-06-15 - CVE-2026-40798 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD
2026-06-18 - EPSS score recorded at 0.283% (percentile 19.84)

Technical Details for CVE-2026-40798

Vulnerability Analysis

The vulnerability is a server-side SQL injection in the wpForo Forum plugin's request handling path. Attacker-controlled input is concatenated into SQL queries without adequate parameterization or sanitization. Because exploitation requires no authentication and no user interaction, any internet-facing WordPress site running wpForo <= 3.0.4 is reachable by an attacker who can issue HTTP requests to forum endpoints. The CVSS scope change indicates that database-layer impact can extend beyond the plugin's own data into the broader WordPress database, which stores user credentials, session tokens, and site configuration.

Root Cause

The root cause is improper neutralization of special elements in SQL queries ([CWE-89]). Plugin code constructs SQL statements using untrusted request parameters without using $wpdb->prepare() placeholders or equivalent escaping primitives. As a result, SQL metacharacters supplied by the client are interpreted by the MySQL/MariaDB backend instead of being treated as literal data.

Attack Vector

Exploitation is performed remotely over HTTP or HTTPS against the WordPress site hosting wpForo. An attacker submits crafted query string or POST parameters to a vulnerable forum endpoint. The injected SQL is then executed in the context of the WordPress database user. Typical post-exploitation activity includes UNION-based extraction of rows from wp_users and wp_usermeta, boolean-based blind enumeration of forum and account data, and time-based probes against the database to confirm injection without visible output. Refer to the Patchstack advisory for wpForo Forum 3.0.4 SQL Injection for technical details.

Detection Methods for CVE-2026-40798

Indicators of Compromise

HTTP requests to wpForo endpoints containing SQL metacharacters such as UNION SELECT, SLEEP(, BENCHMARK(, --, /*, or INFORMATION_SCHEMA in parameter values
Sudden spikes of 500 responses or anomalously long response times from forum URLs, indicating time-based blind injection probes
Web server access logs showing repeated, parameter-fuzzing requests from a small set of source IPs against the same forum route
New or modified WordPress administrator accounts in wp_users shortly after suspicious forum traffic

Detection Strategies

Deploy WAF or reverse-proxy rules that flag SQL injection patterns on URLs containing the wpforo path segment
Enable MySQL general or slow query logging on the WordPress database and alert on queries containing UNION SELECT originating from the WordPress user
Correlate web access logs with database error logs to identify malformed queries triggered by the plugin

Monitoring Recommendations

Monitor for outbound requests from the WordPress host to attacker-controlled infrastructure following suspicious forum traffic
Track creation of new administrative users, changes to wp_options (for example siteurl, home), and additions to active_plugins
Forward web, application, and database logs to a centralized analytics platform and retain them long enough to investigate delayed exploitation

How to Mitigate CVE-2026-40798

Immediate Actions Required

Upgrade the wpForo Forum plugin to a fixed release later than 3.0.4 as published by the vendor; consult the Patchstack advisory for the patched version
If a fixed version is not yet available, deactivate and remove the wpForo plugin from production sites
Rotate WordPress administrator passwords, API keys, and secret salts in wp-config.php after patching to invalidate any credentials exposed via injection

Patch Information

A fix is tracked through the Patchstack vulnerability database entry for wpForo. Site operators should apply the vendor-supplied update for versions above 3.0.4 as soon as it is available, then verify the installed plugin version under WordPress's Plugins screen. After patching, audit the database for unauthorized changes introduced during the exposure window.

Workarounds

Place the WordPress site behind a WAF with active SQL injection signatures and restrict access to wpForo routes
Restrict the WordPress database account to least-privilege, removing FILE, CREATE USER, and superuser capabilities to limit post-exploitation impact
Block requests to wpForo endpoints from anonymous sources until the plugin is updated, for example by requiring authentication at the reverse proxy

bash

# Example WAF rule blocking common SQLi tokens on wpForo paths (ModSecurity)
SecRule REQUEST_URI "@contains /wpforo" \
    "phase:2,deny,status:403,id:1040798,\
    chain,msg:'Possible wpForo SQLi (CVE-2026-40798)'"
    SecRule ARGS "@rx (?i)(union(\s|/\*.*\*/)+select|sleep\s*\(|benchmark\s*\(|information_schema|--\s|/\*)"