CVE-2026-96649 in Frontend Post Submission Manager Lite Plugin
Summary
by MITRE • 09/30/2026
The Frontend Post Submission Manager Lite – Frontend Posting WordPress Plugin plugin for WordPress is vulnerable to Stored DOM-Based Cross-Site Scripting via post_content Parameter (data-label DOM Sink) in all versions up to, and including, 1.3.4 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This requires the site operator to have enabled guest post submission via the [fpsm] shortcode, which registers a publicly accessible AJAX handler gated only by a nonce emitted on every page containing the shortcode.
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Analysis
by VulDB Data Team • 09/30/2026
The Frontend Post Submission Manager Lite plugin for WordPress contains a critical security vulnerability classified as Stored DOM-Based Cross-Site Scripting within versions up to and including 1.3.4. This flaw stems from insufficient input sanitization and output escaping mechanisms when processing data submitted through the post_content parameter, specifically targeting the data-label DOM sink. The nature of this vulnerability allows unauthenticated attackers to inject arbitrary web scripts into pages that are subsequently executed whenever a user accesses an affected page containing the injected content. For exploitation to be successful, the site operator must have enabled guest post submission functionality via the [fpsm] shortcode, which registers a publicly accessible AJAX handler. Although this handler is gated by a nonce emitted on every page containing the shortcode, attackers can bypass this protection through social engineering or other means to obtain valid nonces, thereby facilitating the injection of malicious scripts into the system's stored data.
From a technical perspective, the vulnerability arises because the plugin fails to properly sanitize user-supplied input before storing it in the database and subsequently renders that content without adequate escaping when displaying it back to users via JavaScript DOM manipulation. This sequence creates a classic Stored XSS scenario where the malicious payload is persisted on the server side rather than being transiently passed through URL parameters or headers. When an administrator, editor, or any other user with access privileges views the compromised page, their browser executes the injected script in the context of the site's domain. This can lead to session hijacking, credential theft, defacement of the website, or further propagation of malware if the attacker gains sufficient control over the client-side environment. The reliance on a nonce for protection is undermined by the fact that nonces are often predictable or retrievable through simple page requests, making them an insufficient barrier against determined attackers seeking to exploit this specific DOM sink.
The operational impact of this vulnerability extends beyond immediate script execution. Attackers can leverage the injected scripts to perform actions on behalf of authenticated users, such as creating new posts with malicious content, modifying existing site configurations, or stealing sensitive information like cookies and authentication tokens. This compromises the integrity and confidentiality of the WordPress installation and potentially affects all users who interact with the compromised pages. In enterprise environments, this could lead to significant data breaches, reputational damage, and compliance violations depending on the nature of the stored content and the sensitivity of the user base accessing it. The ability for unauthenticated actors to inject persistent malicious code highlights a severe lapse in secure coding practices regarding input validation and output encoding within the plugin's architecture.
To mitigate this vulnerability, immediate action is required by site administrators who are using versions of Frontend Post Submission Manager Lite up to 1.3.4. The primary remediation step involves upgrading the plugin to version 1.3.5 or later, where these input sanitization and output escaping issues have been addressed by the developers. Until an update can be applied, site operators should consider disabling guest post submission features if they are not strictly necessary for their operations. Additionally, implementing a Web Application Firewall with robust XSS detection rules may help block some of the initial injection attempts before they reach the vulnerable code paths. It is also advisable to review server logs for signs of exploitation and rotate any potentially compromised credentials or session tokens. Long-term mitigation strategies should include adopting secure coding standards that mandate strict input validation against known safe patterns and consistent output encoding based on the context in which data is rendered, aligning with industry best practices outlined by OWASP and CWE classifications related to cross-site scripting vulnerabilities.