CVE-2026-4020 | defend.network

What is CVE-2026-4020?

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.

CVSS7.5 NVD 3.1

SeverityHIGH

ExploitationNo exploitation reported

EPSS40% · P98

Triage statusNo Known Exploit

ActionPatch within 48 hours

CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

NVD published2026-03-31

NVD last modified2026-06-17

Timeline

2026-03-31Published to the U.S. National Vulnerability Database (NVD)
2026-06-17NVD record last updated
2026-06-21First covered in a defend.network daily briefing

Affected product

See advisory

Remediation Steps

Apply the vendor security update for WordPress Gravity SMTP as a priority.
Restrict network exposure of the affected service to trusted sources until patched.
Review logs and detections for indicators of exploitation.
Confirm fixed versions against the official vendor advisory before deploying.

References

Referenced in our briefings & reports

Vulnerability Priority Report – Week 4 of June 2026 (June 22 – 28)
Vulnerability Priority Report – Week 3 of June 2026 (June 15 – 21)
AI Agent Exploitation, SocGholish Disruption, Klue Salesforce Breach (2026-06-22)
BlueNoroff npm supply chain attack; WordPress Gravity SMTP exploited on 100k sites (2026-06-21)

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🤖 This CVE page is generated by defend.network from NVD, CISA KEV, EPSS, and our verified daily briefings. Severity and exploitation data come from official sources; always verify remediation steps against the official vendor advisory before acting in production.