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CVE-2026-78003 – Server-Side Request Forgery (SSRF) / Potential Admin Account Takeover – Mailgun for

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Summary

CVE-2026-78003 is a critical Server-Side Request Forgery (SSRF) vulnerability, achieved via path traversal, in the Mailgun for WordPress plugin. It affects all versions up to and including 2.2.0 and allows unauthenticated attackers to make authenticated requests to arbitrary Mailgun API endpoints using the victim site’s stored API key. The flaw carries a CVSS v3.1 score of 9.8 (Critical) and can be leveraged to intercept password-reset emails and take over administrator accounts.

Technical details

  • Root cause: the plugin’s add_list() function insufficiently validates user-controlled array keys taken from $_POST['addresses'], passing them only through sanitize_text_field() before using them to construct a request path.
  • Trigger conditions: an attacker submits a crafted POST request containing manipulated array keys in the addresses parameter to the vulnerable AJAX/admin handler; no authentication is required.
  • Attack vector: Network (AV:N), low complexity, no privileges or user interaction required.
  • Impact: the manipulated input allows path traversal that redirects the plugin’s authenticated Mailgun API call to an attacker-chosen endpoint or resource, including creating inbound email-forwarding routes on the site’s Mailgun account. This can be used to intercept password-reset emails and ultimately achieve full administrator account takeover on the WordPress site.

Affected software

  • Mailgun for WordPress plugin: all versions up to and including 2.2.0

Severity

  • CVSS v3.1 Base Score: 9.8 (Critical)
  • Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Mitigation and recommended actions

  • Immediate: upgrade the Mailgun for WordPress plugin to version 2.2.1 or later, where this issue is addressed.
  • If immediate patching is not possible: disable or deactivate the Mailgun plugin until the update can be applied, restrict access to WordPress admin-ajax endpoints where feasible, and monitor Mailgun account routing/mailing-list configuration for unauthorized changes.
  • Post-remediation: rotate the site’s Mailgun API key and review Mailgun-configured routes and mailing lists for any unauthorized entries created before patching.

How IONIX identifies potentially affected assets

IONIX matches the following signal against data already collected when it crawled the asset; identifying the technology sends no request beyond that crawl.

  • Raw response body: /wp-content/plugins/mailgun/

References

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1

Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

2

Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

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Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

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