CVE-2026-105857 in PayloadCMS
Summary
by MITRE • 10/06/2026
Payload is a free and open source headless content management system. In @payloadcms/plugin-form-builder versions before 3.90.0 and canary versions before 4.0.0-canary.34, an attacker can craft a form submission that executes code remotely on the server. This issue is fixed in versions 3.90.0 and 4.0.0-canary.34.
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Analysis
by VulDB Data Team • 10/06/2026
Payload CMS is a widely adopted headless content management system built on Node.js, offering developers flexibility in managing digital assets and data structures. Within this ecosystem, the plugin-form-builder module provides functionality for creating and handling user-submitted forms. A critical security vulnerability was identified in versions of this plugin prior to 3.90.0 and canary releases before 4.0.0-canary.34. This flaw represents a severe server-side risk where an attacker could exploit the form submission mechanism to achieve remote code execution on the host system running Payload CMS.
The technical root cause of this vulnerability lies in insufficient input validation and sanitization within the form processing logic. When users submit forms, the plugin processes the provided data fields without adequately restricting potentially malicious payloads embedded within standard text inputs or file metadata. An attacker can craft a specially constructed submission that includes executable code snippets disguised as legitimate form data. Because the backend server processes these submissions with elevated privileges typical of application servers, the injected code is executed in the context of the running Node.js process. This bypasses normal security boundaries and allows for arbitrary command execution on the underlying operating system.
The operational impact of this vulnerability is catastrophic for any organization relying on Payload CMS to host public-facing forms. Successful exploitation grants an attacker full control over the server environment, enabling them to exfiltrate sensitive data stored within the content management system, modify or delete records, install backdoors, and pivot into other internal network segments. Since headless CMS platforms often serve as central hubs for digital assets and user-generated content, compromising one instance can lead to widespread data breaches and service disruptions. The ability to execute code remotely means that automated scanning tools could potentially identify vulnerable instances and exploit them without manual intervention, increasing the likelihood of large-scale attacks.
This vulnerability aligns with CWE-94 Improper Control of Generation of Code or Command, specifically server-side injection scenarios where untrusted data is used as part of a command or script execution context. From an offensive security perspective, this behavior corresponds to ATT&CK technique T1059 Command and Scripting Interpreter, which describes how adversaries use system utilities like JavaScript engines to execute malicious commands after gaining initial access through the application layer. The lack of strict schema validation for form fields allows attackers to bypass typical web application firewalls that might otherwise block obvious script tags or SQL injection patterns, as the payload is processed by the server-side runtime rather than being rendered in a browser context.
Mitigation strategies must prioritize immediate version upgrades and rigorous input hygiene. Organizations running affected versions of plugin-form-builder should upgrade to version 3.90.0 or later, which includes patches for this specific code execution flaw. For those unable to update immediately due to dependency constraints, implementing strict schema validation using libraries like Zod or Joi at the application layer can help filter out dangerous characters and structures before they reach the vulnerable plugin logic. Additionally, deploying a Web Application Firewall with rules tuned to detect server-side injection patterns may provide an additional layer of defense, although it is not a substitute for patching the underlying software vulnerability. Regular security audits and dependency scanning using tools like npm audit or Snyk are recommended to maintain visibility over such risks in open-source dependencies.