CVE-2026-90984 in Generate PDF using Contact Form 7 Plugin
Summary
by MITRE • 09/18/2026
The Generate PDF using Contact Form 7 WordPress plugin before 4.2.2 does not restrict the destination of the image fetch its PDF renderer performs on submitted form content, allowing unauthenticated users to make the server request internal resources and read the response back through the generated PDF.
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Analysis
by VulDB Data Team • 09/18/2026
The vulnerability identified in versions of the Generate PDF using Contact Form 7 WordPress plugin prior to version 4.2.2 represents a critical Server-Side Request Forgery (SSRF) flaw rooted in inadequate input validation within the document generation module. This security defect allows unauthenticated attackers to manipulate the image fetching mechanism employed by the PDF renderer, effectively bypassing standard network access controls that are typically enforced on server-side applications. By exploiting this misconfiguration, an attacker can instruct the vulnerable application to retrieve content from arbitrary destinations rather than limiting requests to external or permitted internal resources. This capability transforms a seemingly benign feature for generating downloadable documents into a powerful vector for unauthorized data exfiltration and internal network reconnaissance.
From a technical perspective, the core issue lies in how the plugin processes image URLs embedded within contact form submissions before passing them to the PDF generation library. The renderer does not perform sufficient validation on the scheme or host of these URLs, nor does it implement an allowlist for permitted domains. Consequently, when a user submits a form containing an image tag with a maliciously crafted source attribute pointing to localhost, 127.0.0.1, or other private IP ranges, the server executes the request on behalf of the attacker. The resulting PDF file then embeds this retrieved content, allowing the attacker to read sensitive internal responses directly through the generated document output. This mechanism bypasses browser-based Same-Origin Policy restrictions because the requests are initiated by the backend PHP process rather than a client-side script.
The operational impact of this vulnerability is severe due to its unauthenticated nature and potential for data leakage. Attackers can target internal services that lack external-facing authentication, such as database administration interfaces, cloud metadata endpoints like AWS EC2 instance metadata service (IMDSv1), or internal API gateways. By fetching credentials, configuration files, or sensitive business logic from these internal resources via the PDF generation endpoint, an attacker gains unauthorized access to critical infrastructure components. This can lead to full system compromise if combined with other vulnerabilities, as it provides a reliable method for probing and extracting data from networks that are otherwise isolated from direct internet access. The ability to read responses back through the generated PDF ensures that even binary or structured data formats like JSON or XML containing sensitive information remain accessible to the attacker without requiring complex out-of-band channels.
This vulnerability aligns with CWE-918, which describes Server-Side Request Forgery (SSRF) flaws where a web application fetches a remote resource without validating the user-supplied URL. It also maps directly to MITRE ATT&CK technique T1557, specifically Adversary-in-the-Middle or Lateral Tool Transfer variants that leverage SSRF for internal network discovery and credential harvesting. The lack of authentication requirements further exacerbates the risk, classifying it under CWE-862 regarding missing authorization checks in critical functions. Organizations relying on this plugin are exposed to significant risks as any visitor can trigger these requests without prior login or token validation.
Mitigation strategies must prioritize immediate patching and architectural hardening. The most effective remediation is upgrading the Generate PDF using Contact Form 7 plugin to version 4.2.2 or later, where developers have implemented strict URL validation and allowlisting mechanisms for image sources. In cases where updating is not immediately feasible, administrators should implement a Web Application Firewall (WAF) rule set that blocks outbound requests from the web server process to private IP ranges such as 10.x.x.x, 172.16.x.x through 172.31.x.x, and 192.168.x.x. Additionally, configuring PHP settings to disable remote file inclusion functions like allow_url_fopen can provide a layer of defense against similar SSRF vectors across the entire application stack. Regular security audits focusing on input validation in document generation modules are essential to prevent recurrence of such flaws in WordPress ecosystems.