CVE-2026-15990 in Formidable Charts Plugin
Summary
by MITRE • 08/26/2026
The Formidable Charts plugin for WordPress is vulnerable to Directory Traversal in all versions up to, and including, 2.0.1 via the 'frm_graph' parameter. This makes it possible for unauthenticated attackers to read the contents of arbitrary files on the server, which can contain sensitive information. Successful exploitation requires Formidable Forms Lite, Formidable Forms Pro, and Formidable Charts to be active and requires the wp-content/uploads/frm-charts/ directory to exist, normally after an image-format chart is rendered.
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Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified in the Formidable Charts plugin for WordPress represents a critical security flaw classified as Directory Traversal, which corresponds to CWE-22 in the Common Weakness Enumeration standard. This specific weakness allows attackers to access files and directories that are stored outside the web root folder, potentially leading to unauthorized disclosure of sensitive information or system compromise. The vulnerability exists within all versions up to and including 2.0.1 and is triggered through the manipulation of the frm_graph parameter. In a typical WordPress environment, plugins often handle user-supplied input for rendering dynamic content such as charts or graphs. When this input is not properly sanitized before being used in file system operations, it creates an opportunity for path traversal attacks where special characters like dot-dot-slash sequences can be injected to navigate up the directory tree and access restricted areas of the server's filesystem.
From a technical perspective, the exploitation mechanism relies on the application failing to validate or restrict the paths provided via the frm_graph parameter. By injecting specific sequence patterns into this input field, an unauthenticated attacker can instruct the underlying PHP functions to read files located in arbitrary directories rather than just within the intended upload folder. This lack of strict input validation is a common oversight in plugin development where dynamic file inclusion or reading operations are performed based on user control without adequate boundary checks. The impact of such a flaw extends beyond simple data leakage; it can serve as an initial vector for more severe attacks, including remote code execution if sensitive configuration files containing database credentials or API keys are accessed and subsequently exploited by the attacker to gain deeper access into the infrastructure.
The operational prerequisites for exploiting this vulnerability include having Formidable Forms Lite, Formidable Forms Pro, and Formidable Charts all active on the target WordPress installation. Additionally, successful exploitation requires that the wp-content/uploads/frm-charts directory exists, which typically occurs after an image-format chart has been rendered by a legitimate user or administrator. This dependency means that while the vulnerability is present in older versions of the plugin, its exploitability is contingent upon specific environmental conditions being met on the target server. Despite these prerequisites, the fact that no authentication is required makes this a high-risk issue for any public-facing WordPress site running the affected software stack. Attackers can probe for this condition remotely without needing valid credentials, increasing the likelihood of successful exploitation in automated scanning campaigns.
In terms of threat intelligence and attack patterns, this vulnerability aligns with techniques observed in various cyber-attack frameworks such as MITRE ATT&CK, specifically relating to Discovery tactics where adversaries seek to gather information about the target environment. The ability to read arbitrary files facilitates reconnaissance efforts that can lead to further compromise steps like Credential Access or Lateral Movement within a compromised network segment. Organizations relying on WordPress for their digital presence must recognize that even seemingly minor plugins with limited functionality can introduce significant risks if they contain fundamental input validation errors.
To mitigate this risk, immediate action is required by updating the Formidable Charts plugin to version 2.0.2 or later where the issue has been addressed through improved input sanitization and path restriction mechanisms. Administrators should verify that all related plugins including Formidable Forms Lite and Pro are also kept up-to-date to ensure consistent security posture across the entire form-handling ecosystem. Furthermore, implementing web application firewalls can provide an additional layer of defense by detecting and blocking common directory traversal patterns in HTTP requests before they reach the application logic. Regular auditing of plugin code for proper file path handling practices is essential to prevent similar vulnerabilities from being introduced in future updates or other plugins within the same environment.