Hackers Exploit Gravity SMTP WordPress Plugin Bug to Expose API Keys
Threat actors are exploiting a recently patched security flaw impacting Gravity SMTP, a WordPress plugin that's installed on about 100,000 sites. The vulnerability, tracked as CVE-2026-4020 (CVSS score: 5.3), is a medium-severity information disclosure flaw that can allow unauthenticated attackers to extract sensitive data, such as configuration data, API keys, secrets, and OAuth tokens configured for the plugin's email integrations. "This is due to a REST API endpoint registered at /wp-json/gravitysmtp/v1/tests/mock-data with a permission_callback that unconditionally returns true, allowing any unauthenticated visitor to access it," Wordfence said . "When the ?page=gravitysmtp-settings query parameter is appended, the plugin's register_connector_data() method populates internal connector data, causing the endpoint to return approximately 365 KB of JSON containing the full System Report." As a result, an unauthenticated attacker can weaponize ...
î Jun 20, 2026