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Mailgun for WordPress EUVDEUVD-2026-64242

| CVE-2026-78003 CRITICAL
Server-Side Request Forgery (SSRF) (CWE-918)
2026-08-22 Wordfence GHSA-jr9c-873v-948h
9.8
CVSS 3.1 · Vendor: Wordfence
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Send crafted unauthenticated POST to add_list endpoint
  2. Delivery
    Path-traversal in $_POST['addresses'] keys
  3. Exploit
    Server calls Mailgun API with site key
  4. Execution
    Create inbound email-forwarding route
  5. Persist
    Trigger admin password reset, intercept email
  6. Impact
    Reset admin credentials, full site takeover

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V4 - API and Web Service URL allowlisting, SSRF prevention
MITRE ATT&CK

2 techniques across 2 tactics: Initial Access, Credential Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

The target must have the Mailgun for WordPress plugin (≤ 2.2.0) installed AND configured with a valid Mailgun API key - without a stored key there is nothing for the SSRF to abuse, so this is the key limiting factor. Exploitation reaches the vulnerable add_list() function via user-controlled array keys in $_POST['addresses'], and full administrator takeover additionally depends on WordPress using Mailgun for outbound mail so that password-reset messages traverse the attacker-created inbound route. Per the CVSS vector (AV:N/AC:L/PR:N/UI:N) no authentication or user interaction is required, and default plugin behavior is affected once a key is configured.

Impact

The signals are broadly consistent and point to genuine high priority. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, score 9.8) indicates remote, low-complexity, unauthenticated exploitation, matching the description's 'unauthenticated attackers.' The realistic impact - hijacking the site's Mailgun key to reroute password-reset email and seize an admin account - supports high confidentiality and integrity impact; the assigned A:H (availability) is less clearly justified by the described attack, which is takeover- rather than denial-focused. No EPSS score, no CISA KEV entry, and no public POC were provided, so real-world exploitation is not confirmed - this is a high-severity, credible issue rather than an evidenced mass-exploitation event. The one caveat: exploitation is only meaningful when the plugin is actually configured with a valid Mailgun API key, which the CVSS 'no conditions' framing does not capture.

Exploit ScenarioDerived

An attacker sends a crafted unauthenticated POST request to the vulnerable endpoint with path-traversal sequences embedded in the $_POST['addresses'] array keys, steering the server's Mailgun API call to the routes-creation endpoint. Using the site's own stored API key, the server creates an inbound forwarding route that copies password-reset emails to the attacker; the attacker then triggers a password reset for the admin account, captures the link, and takes over the site. Given AV:N/AC:L/PR:N, this requires only network access and no authentication or user interaction, though no public POC is currently identified.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.
No patch listed yet 0.5% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 22, 2026

Server-Side Request Forgery in the Mailgun for WordPress plugin (versions up to and including 2.2.0) lets unauthenticated attackers coerce the WordPress server into making authenticated requests to arbitrary Mailgun API endpoints using the site's own stored API key. Because the add_list() function trusts user-controlled array keys from $_POST['addresses'] and only runs them through sanitize_text_field(), an attacker can path-traverse to any Mailgun endpoint - notably creating inbound email-forwarding routes to intercept password-reset messages and take over the administrator account. Reported by Wordfence with a CVSS of 9.8; no public exploit identified at time of analysis and no CISA KEV listing.

RemediationAI

No vendor-released patched version is identified in the available data - the description marks 2.2.0 as the highest vulnerable version but does not name a fixed release, so upgrade to the latest available Mailgun for WordPress version and confirm against the Wordfence advisory (https://www.wordfence.com/threat-intel/vulnerabilities/id/110e888d-69fc-4682-b908-2b62288c5227?source=cve) that it post-dates 2.2.0 before relying on it. As compensating controls until a confirmed fix is applied: rotate the Mailgun API key and scope it to least privilege in the Mailgun dashboard to limit what a coerced request can do; audit and delete any unexpected inbound Mailgun routes (especially email-forwarding routes) and enable alerting on route changes; place the WordPress admin-ajax/plugin endpoint that reaches add_list() behind a WAF rule blocking path-traversal sequences in the 'addresses' parameter; and consider temporarily deactivating the plugin if Mailgun integration is non-essential, accepting the trade-off of losing Mailgun-based email delivery.

Affected VersionsENISA

Mailgun for WordPress 0 ≤2.2.0

Affected Packages

euvd mailgun_for_wordpress no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The affected component is the Mailgun for WordPress plugin (cpe:2.3:a:mailgun:mailgun_for_wordpress), which integrates a WordPress site's transactional email with Mailgun's HTTP API. The root cause is CWE-918 (SSRF): the add_list() handler builds a Mailgun API request path from attacker-supplied array keys in $_POST['addresses'] and passes them only through sanitize_text_field(), which strips tags and normalizes whitespace but does NOT neutralize path-traversal sequences or restrict the target endpoint. This turns the plugin into a confused deputy - the server holds a privileged Mailgun API key, and the attacker steers where that key is used. The trac references (mailgun.php lines 259, 323, 331, 557 in trunk and tag 2.1.10) point to the request-construction and sanitization code paths involved.

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Severity by source

Vendor (Wordfence) PRIMARY 9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 9.1 CRITICAL

Remote unauthenticated, low complexity, no UI (AV:N/AC:L/PR:N/UI:N); API-key abuse yields admin takeover so C:H/I:H, but no described availability impact so A:N.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (Wordfence).

CVSS VectorVendor: Wordfence

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

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.

Executive ViewAI

Why It Matters

The Mailgun for WordPress plugin (versions ≤2.2.0) contains a critical unauthenticated vulnerability enabling attackers to hijack WordPress administrator accounts and gain complete control of affected websites. Any organization running this plugin faces immediate risk of full site compromise, data breach, and potential reputational damage without remediation.

Business Impact: Severe
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: (1) immediately uninstall or disable the plugin; (2) if business-critical, deploy a Web Application Firewall rule blocking POST requests containing Mailgun API paths; (3) restrict administrator panel access by IP address; (4) enforce multi-factor authentication on all administrative accounts to prevent account takeover if password-reset emails are intercepted; (5) monitor outbound API requests to Mailgun endpoints for anomalous activity indicating exploitation attempts.

Threat Intelligence Overview

EPSS Score
0.5%
Top 57% exploitable
Prevalence
Medium
Mailgun integration plugin, common on WordPress sites using Mailgun email
Social Media
8
Sightings
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.5%
Patch available No
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Out-of-Cycle
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact
Very High
Technical Impact
Total

Priority Score

50
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Server-Side Request Forgery exploits applications that fetch remote resources based on user-supplied URLs.

Path traversal exploits occur when applications use user-controlled input to construct file system paths without proper validation.

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