Mailgun for WordPress <= 2.2.0 - Unauthenticated Server-Side Request Forgery (SSRF) via 'addresses' Array Keys
Strategic Overview
- Status
- Patched in 2.2.1
- Affected Plugin
- Mailgun for WordPress
- Affected Version
<= 2.2.0- CVSS
- 9.8Critical
- Weakness type
- CWE-918 · Server-Side Request Forgery (SSRF)
- CVE
CVE-2026-78003
At a glance
CVE-2026-78003 is a critical-severity Server-Side Request Forgery (SSRF) vulnerability in the Mailgun for WordPress WordPress plugin, affecting versions <= 2.2.0. It carries a CVSS score of 9.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 2.2.1; sites on affected versions should update now. Disclosed August 2026, reported by Osvaldo Noe Gonzalez Del Rio (Os).
Vulnerability Overview
The Mailgun for WordPress plugin for WordPress is vulnerable to Server-Side Request Forgery (SSRF) via path traversal in versions up to and including 2.2.0. This is due to insufficient input validation in the add_list() function, which accepts user-controlled array keys from $_POST['addresses'], passes them through sanitize_text_field(). This makes it possible for unauthenticated attackers to make authenticated POST requests to any Mailgun API endpoint using the WordPress site's API key, including creating inbound email-forwarding routes that can intercept password reset emails, leading to administrator account takeover.
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.
CWE-918: Server-Side Request Forgery (SSRF)
Mailgun for WordPress <= 2.2.0 carries this weakness at addresses, and reaching it takes no account at all. Server-side request forgery means the application fetches a URL supplied by the caller, turning the server into a proxy for requests the attacker could not make directly.
The request originates from inside the hosting network, which is how these flaws reach cloud metadata endpoints, internal admin panels and services that trust local traffic. For Mailgun for WordPress the fix is 2.2.1: builds <= 2.2.0 are affected, anything from 2.2.1 onward is not.
Remediation
Update to version 2.2.1, or a newer patched version
How does WordSec protect against this?
Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Mailgun for WordPress 2.2.1 closes this, and updating the plugin is the step that ends it.
- Firewall
- Login Security
- Alerts
External References
Related records
Other vulnerabilities in Mailgun for WordPress
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