CVE-2026-109652 in ERPNext
Summary
by MITRE • 10/13/2026
Frappe ERPNext before 15.119.1 and 16.x before 16.32.0 contains a server-side template injection vulnerability because user-controlled message fields are not validated before template rendering, allowing expressions to run in an unrestricted context. Authenticated attackers holding a common operational role can inject template expressions to read and write arbitrary database data, delete documents, send outbound requests from the server, and send mail from the site.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability identified in Frappe ERPNext versions prior to 15.119.1 and 16.x prior to 16.32.0 represents a critical Server-Side Template Injection (SSTI) flaw within the application's messaging subsystem. This security defect stems from an insufficient validation mechanism applied to user-controlled message fields before they are processed by the server-side template engine. In typical web applications, input data is expected to be treated as plain text or strictly sanitized before integration into dynamic content generation logic. However, in this specific implementation of ERPNext, the framework fails to distinguish between literal string values and executable template expressions when rendering messages. This architectural oversight allows an attacker who has successfully authenticated with a standard operational role to inject malicious code directly into message payloads that are subsequently rendered by the server's templating engine without adequate sanitization or context switching.
From a technical perspective, this vulnerability aligns closely with CWE-94, which describes Improper Control of Generation of Code (Code Injection), and more specifically falls under the category of Server-Side Template Injection as defined in various security taxonomies. The core issue lies in the template engine's ability to interpret injected syntax as executable commands rather than static data. When an authenticated user submits a message containing specific template delimiters or expression patterns, the server processes these inputs within its execution context. Because the validation layer is bypassed or absent for this particular input vector, the injected expressions are evaluated by the backend processor. This capability transforms what appears to be a simple communication channel into a powerful remote code execution interface, albeit constrained by the permissions of the authenticated user account and the capabilities exposed through the template engine's API.
The operational impact of this vulnerability is severe due to the breadth of actions an attacker can perform once they have established control over the template rendering process. An adversary holding even a common operational role, such as a standard employee or manager within the ERP system, can leverage this flaw to achieve significant compromise of the underlying infrastructure and data integrity. Specifically, the ability to execute arbitrary expressions allows for reading sensitive database records that may contain personally identifiable information, financial details, or proprietary business logic. Furthermore, attackers are not limited to passive data exfiltration; they possess write capabilities that enable them to modify or delete critical documents stored within the ERPNext database. This level of access undermines the fundamental principles of integrity and availability required for enterprise resource planning systems.
Beyond direct manipulation of local data, this vulnerability facilitates outbound network interactions initiated from the server itself. Attackers can craft template expressions that trigger HTTP requests to external domains controlled by them. This capability effectively turns the ERPNext instance into a pivot point or botnet node, allowing for further reconnaissance against internal networks, exfiltration of session cookies via cross-site request forgery mechanisms, or interaction with command-and-control infrastructure. Additionally, the ability to send emails from the site means that attackers can abuse the organization's legitimate email reputation to launch phishing campaigns against other employees or external partners, thereby expanding the blast radius of the initial compromise and potentially leading to broader organizational security incidents such as credential theft or malware distribution.
Mitigation strategies must prioritize immediate patching alongside temporary compensating controls. The primary remediation is to upgrade Frappe ERPNext to version 15.119.1 or later, or for users on the newer branch, to version 16.32.0 or higher, where these input validation checks have been implemented and template rendering contexts are properly isolated from user-supplied data. For organizations unable to patch immediately due to operational constraints, implementing a Web Application Firewall (WAF) rule set that detects common SSTI payloads within message fields can provide partial protection by blocking requests containing suspicious template syntax patterns such as double curly braces or specific function calls often used in injection attacks. Additionally, enforcing strict Content Security Policy headers and reviewing database access permissions for service accounts may help limit the potential damage if an exploitation attempt occurs. Regular security audits focusing on input validation across all user-facing endpoints are recommended to prevent similar vulnerabilities from being introduced during future development cycles.