CVE-2026-28562: Wpforo Forum SQL Injection Vulnerability

CVE-2026-28562 Overview

CVE-2026-28562 is an unauthenticated SQL injection vulnerability in the wpForo WordPress plugin version 2.4.14 developed by gvectors. The flaw resides in the Topics::get_topics() function, where the ORDER BY clause relies on esc_sql() sanitization that is ineffective against unquoted SQL identifiers. Attackers manipulate the wpfob parameter with CASE WHEN payloads to perform blind boolean-based data extraction from the WordPress database. The vulnerability is tracked under [CWE-89] and affects forum installations exposed to anonymous traffic.

Critical Impact

Unauthenticated attackers can extract WordPress credentials and other sensitive database contents through blind boolean SQL injection over the network.

Affected Products

• gvectors wpForo Forum plugin for WordPress version 2.4.14
• WordPress sites running the vulnerable wpForo plugin with public forum access
• Any deployment exposing the Topics::get_topics() endpoint to unauthenticated users

Discovery Timeline

• 2026-02-28 - CVE-2026-28562 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-28562

Vulnerability Analysis

The vulnerability stems from improper neutralization of special elements used in an SQL command within the Topics::get_topics() method. The plugin accepts a user-controlled wpfob request parameter and incorporates it into the ORDER BY clause of a database query. Developers applied esc_sql() as the sanitization control, but this function only escapes quoted string literals. Unquoted SQL identifiers and expressions pass through unmodified, enabling injection of arbitrary SQL fragments.

The attack is unauthenticated and remotely exploitable, which substantially expands the threat surface for any public WordPress forum running the affected version.

Root Cause

The root cause is incorrect application of esc_sql() to a context where it cannot enforce safety. esc_sql() is designed to escape data placed inside quoted strings within SQL statements. When the value is concatenated into an ORDER BY position as an identifier or expression, no quoting occurs and escape semantics no longer prevent injection. The plugin should instead validate wpfob against a strict allow-list of known column names.

Attack Vector

An attacker submits an HTTP request to the forum endpoint that invokes Topics::get_topics() and supplies a crafted wpfob parameter containing CASE WHEN conditional expressions. Each request yields a boolean signal through differential response behavior, such as ordering changes or content variations. By iterating bit-by-bit, the attacker extracts data including the wp_users table contents, password hashes, and session tokens. No user interaction or authentication is required.

No verified public proof-of-concept code is available for this vulnerability. Technical details are documented in the VulnCheck SQL Injection Advisory.

Detection Methods for CVE-2026-28562

Indicators of Compromise

• HTTP requests containing the wpfob parameter with SQL keywords such as CASE, WHEN, SELECT, IF, or SLEEP
• Unusually high volumes of similar requests to forum topic listing endpoints from a single source IP
• Web server access logs showing repeated parameter variations consistent with blind SQL extraction
• Database queries with anomalous ORDER BY clauses containing conditional expressions

Detection Strategies

• Inspect WordPress access logs for requests targeting wpForo endpoints with non-alphanumeric values in wpfob
• Deploy web application firewall rules that match SQL injection patterns in query parameters bound to ordering fields
• Enable MySQL general or slow query logs to capture malformed ORDER BY clauses generated by the plugin
• Correlate failed authentication patterns following suspicious forum traffic spikes

Monitoring Recommendations

• Monitor outbound traffic from WordPress hosts for credential exfiltration signals
• Track request rate and parameter entropy on forum endpoints to detect automated extraction tools
• Alert on changes to administrative accounts or addition of new privileged users in wp_users
• Review WordPress audit logs for unexpected role escalations or password resets after suspicious traffic

How to Mitigate CVE-2026-28562

Immediate Actions Required

• Update the wpForo plugin to a version newer than 2.4.14 once the vendor releases a fix
• Restrict forum access to authenticated users if possible until a patch is applied
• Deploy a web application firewall rule blocking SQL keywords in the wpfob parameter
• Rotate WordPress administrator credentials and database secrets if exploitation is suspected

Patch Information

At the time of publication, no vendor advisory URL is listed in the CVE record. Administrators should monitor the WordPress Plugin wpForo page and the WordPress wpForo Developer Info for an updated release that replaces esc_sql() with strict allow-list validation on ORDER BY identifiers.

Workarounds

• Disable the wpForo plugin until a patched version is available
• Place the WordPress site behind a reverse proxy that strips or validates the wpfob parameter against a column allow-list
• Apply database-level least-privilege so the WordPress account cannot read sensitive tables beyond what the application requires
• Enforce network segmentation isolating the database server from direct internet exposure

# Example ModSecurity rule to block CASE WHEN payloads in wpfob
SecRule ARGS:wpfob "@rx (?i)(case\s+when|select\s|sleep\(|benchmark\()" \
    "id:1002826,phase:2,deny,status:403,log,\
    msg:'wpForo CVE-2026-28562 SQLi attempt blocked'"