Mailgun - Path Traversal (CVE-2026-78003)

Q: Am I affected by this vulnerability?

You are affected if your site runs Mailgun. No account is needed to exploit this, so a public site is reachable by anyone.

Q: How do I fix it?

Update Mailgun to the latest available version. Where the vendor has not yet published a fix, remove or disable the plugin until they do. Until you can update, Request / payload inspection (WAF) in Hack Halt ProSecure contains this class of attack at the request layer.

Q: What can an attacker actually do?

This is a Path Traversal flaw. An attacker who exploits it can read files outside the intended directory, including wp-config.php.

CVE-2026-78003

Vulnerability CVE-2026-78003 PLUGIN mailgun CRITICAL

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.

CVE-2026-78003

CRITICAL CVSS 9.8 Published 2026-08-22 Updated 2026-08-25

AI Risk Critical (100/100) Active Exploit: No strong signal Published Exploit: No public exploit references Priority: P1 Immediate

Severity Band CRITICAL

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

Affected Components 2

Reference Links 9

AI Risk Engine Critical (100/100)

Exploitability Very High

Active Exploitation No strong signal

Published Exploit Status No public exploit references

Threat Timeline

2026-08-22 CVE published and first recorded in the threat feed.
2026-08-25 Record updated with latest vulnerability metadata.
2026-08-23 AI technical context refreshed for mitigation and impact guidance.
Now Monitoring for follow-up changes, linked references, and new related CVEs.

AI Context

Machine-generated threat intelligence

AI Updated 12 days ago

AI enriched 12 days ago (2026-08-23 16:36 UTC)

Technical Summary

Potential Impact

Severity is CRITICAL (CVSS 9.8). Depending on deployment context, affected components may be exposed to unauthorized actions or data integrity risk.

Exploitability Assessment

Exploitability is assessed as Very High based on remote code execution potential, low-bar exploit prerequisites.

Primary risk drivers: remote code execution potential, low-bar exploit prerequisites

Mitigation Recommendations

Validate affected product versions, prioritize patching, and monitor references for vendor remediation guidance. If immediate patching is not possible, apply compensating controls and limit exposure of vulnerable surfaces.

Detection & Monitoring

Track authentication anomalies, unexpected file writes, and suspicious plugin API activity around affected components.

Business Impact Lens

AI risk score 100/100 (Critical, Very High) with priority P1 Immediate. Prioritize remediation where affected components process customer data, admin sessions, or Internet-exposed workflows.

Affected Products

Mailgun PLUGIN · mailgun Affected: <= 2.2.0 Fixed version not specified

Mailgun For Wordpress PLUGIN · mailgun-for-wordpress Affected: <= 2.2.0 Fixed version not specified

References

What to do about this

Patch immediately Serious, and reachable without meaningful privilege.

Fix it

Update Mailgun to the latest available version.

Where the vendor has not published a fix yet, disable the plugin until they do.

Cannot update today? Request / payload inspection (WAF) in Hack Halt ProSecure blocks this class of attack before WordPress processes the request.

Inspect request parameters and bodies for injection, traversal and file-inclusion payloads, and refuse the request rather than logging it.

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