CVE-2026-42740 Overview
CVE-2026-42740 is a Blind SQL Injection vulnerability in the Tainacan WordPress plugin. The flaw stems from improper neutralization of special elements used in SQL commands [CWE-89]. It affects all Tainacan versions up to and including 1.0.3. Unauthenticated attackers can inject malicious SQL into backend database queries over the network without user interaction. The vulnerability carries a CVSS 3.1 base score of 9.3 and is classified as critical. Because the issue is blind, attackers infer database contents through conditional responses or timing side channels rather than direct output.
Critical Impact
Unauthenticated remote attackers can execute arbitrary SQL queries against the WordPress database, exposing sensitive content and impacting site availability.
Affected Products
- Tainacan WordPress plugin versions up to and including 1.0.3
- WordPress sites running the vulnerable Tainacan plugin
- Any WordPress installation exposing Tainacan endpoints to untrusted networks
Discovery Timeline
- 2026-05-27 - CVE-2026-42740 published to NVD
- 2026-05-27 - Last updated in NVD database
Technical Details for CVE-2026-42740
Vulnerability Analysis
The Tainacan plugin fails to sanitize user-supplied input before passing it into SQL statements executed against the WordPress database. An attacker crafts HTTP requests containing SQL metacharacters that alter the structure of backend queries. Because the vulnerable endpoint does not return query results directly, exploitation relies on Blind SQL Injection techniques. Attackers infer data by observing boolean response differences or by inducing time delays with database functions such as SLEEP() or BENCHMARK(). The Scope value of Changed in the CVSS vector reflects that the database can hold data belonging to multiple WordPress sites or tenants beyond the vulnerable plugin's boundary.
Root Cause
The root cause is the use of unparameterized SQL queries that concatenate untrusted request parameters directly into statement strings. The plugin does not apply prepared statements through $wpdb->prepare() or equivalent escaping. This violates secure coding practices for WordPress plugin database access and creates an injection sink reachable from network requests.
Attack Vector
The attack vector is Network with Low complexity and no privileges or user interaction required. An attacker sends crafted HTTP requests to vulnerable Tainacan endpoints exposed by the WordPress site. The vulnerability mechanism is described in the Patchstack SQL Injection Vulnerability advisory. No verified public proof-of-concept code is available at the time of writing.
Detection Methods for CVE-2026-42740
Indicators of Compromise
- HTTP requests to Tainacan plugin endpoints containing SQL metacharacters such as single quotes, UNION, SELECT, or boolean operators in parameters
- Repeated requests with subtle parameter variations consistent with blind injection enumeration
- Web server log entries showing requests that trigger unusually long response times, indicating time-based SQL injection probing
- Outbound database queries containing SLEEP, BENCHMARK, or IF constructs originating from plugin code paths
Detection Strategies
- Inspect WordPress access logs and web application firewall (WAF) telemetry for requests targeting Tainacan routes with SQL syntax in parameter values
- Enable MySQL or MariaDB query logging to capture anomalous queries originating from the plugin during suspected attack windows
- Correlate spikes in 500-series HTTP errors with parameter fuzzing patterns against Tainacan endpoints
Monitoring Recommendations
- Alert on response time outliers for Tainacan endpoints, which can indicate time-based blind injection
- Track request volume and source IP diversity for plugin URLs to identify enumeration campaigns
- Forward WordPress, web server, and database logs to a centralized analytics platform for cross-source correlation
How to Mitigate CVE-2026-42740
Immediate Actions Required
- Identify all WordPress sites running the Tainacan plugin at version 1.0.3 or earlier
- Restrict access to Tainacan endpoints from untrusted networks until a patched version is applied
- Deploy WAF rules to block SQL metacharacters and known injection payloads targeting plugin parameters
- Review database and web server logs for evidence of prior exploitation attempts
Patch Information
No fixed version is identified in the NVD record at the time of publication. Site administrators should consult the Patchstack SQL Injection Vulnerability advisory and the official Tainacan plugin repository for an updated release addressing CVE-2026-42740.
Workarounds
- Disable or remove the Tainacan plugin until a verified patched version is available
- Apply virtual patching through a WAF to filter SQL injection patterns on Tainacan request paths
- Restrict database user privileges so the WordPress account cannot read sensitive tables outside the plugin scope
- Enforce network-level access controls limiting administrative and plugin endpoints to trusted source addresses
# Example: temporarily deactivate the Tainacan plugin via WP-CLI
wp plugin deactivate tainacan
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
