CVE-2026-4020
CWE-200Published: March 31, 2026· Updated: Apr 1, 2026
Official Description
The Gravity SMTP plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 2.1.4. 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. 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. This makes it possible for unauthenticated attackers to retrieve detailed system configuration data including PHP version, loaded extensions, web server version, document root path, database server type and version, WordPress version, all active plugins with versions, active theme, WordPress configuration details, database table names, and any API keys/tokens configured in the plugin.
Technical Analysis
CVE-2026-4020 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in complete confidentiality breach (data exposure), with a CVSS base score of 7.5.
CISA has added CVE-2026-4020 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
From a weakness classification perspective (CWE-200): Information exposure vulnerabilities leak sensitive data to unauthorized actors.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
News & Research Mentioning CVE-2026-4020
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 [xlite_meta score:50 src:The Hacker News xlite_fp:2d1fdd6cb681d6bcb7a4647ad74bf1075a9c48f854ef8e7ce3f7cd65ddd683f7]
All References (7)
Quick Facts
Related CVEs (CWE-200)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-4020 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1