CVE-2026-12228 in lollms
Summary
by MITRE • 07/19/2026
A stored cross-site scripting (XSS) vulnerability exists in the `POST /api/prompts/share` endpoint of parisneo/lollms (latest version). The endpoint stores attacker-controlled `prompt_content` into `DBDirectMessage.content` without server-side sanitization. When a victim opens the direct message (DM) thread, the message is rendered by the DM UI through `MessageContentRenderer`, which uses `v-html` to insert rendered HTML into the DOM. The frontend sanitizer, which is regex-based, fails to comprehensively sanitize attacker-controlled HTML, allowing malicious payloads to execute in the victim's browser context. This vulnerability enables any authenticated user to send a malicious prompt-share message to another user's inbox, leading to arbitrary JavaScript execution, authenticated actions as the victim, exposure of same-origin application data, and potential account takeover.
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Analysis
by VulDB Data Team • 07/19/2026
The vulnerability under examination represents a critical stored cross-site scripting flaw within the parisneo/lollms application framework, specifically affecting the POST /api/prompts/share endpoint. This endpoint serves as a mechanism for sharing prompts between authenticated users, yet fails to implement proper input validation and sanitization measures when processing the prompt_content parameter. The flaw resides in the server-side architecture where user-supplied content is directly persisted to the database without adequate sanitization, creating a persistent vector for malicious code injection that can be executed against any user who accesses the compromised message.
The technical implementation of this vulnerability stems from the application's reliance on client-side regex-based sanitization mechanisms within the MessageContentRenderer component. When victims access direct message threads containing malicious content, the frontend rendering process utilizes v-html directives to inject HTML content directly into the DOM structure. This approach bypasses native browser XSS protections and creates an environment where attacker-controlled HTML can execute with the privileges of the authenticated user. The regex-based sanitizer proves insufficient against sophisticated attack vectors that can evade pattern matching mechanisms, particularly when dealing with encoded or obfuscated payloads that maintain their malicious intent while appearing benign to simple pattern recognition systems.
The operational impact of this vulnerability extends far beyond simple script execution, as it enables authenticated users to perform arbitrary actions within the application context of their victims. Successful exploitation allows attackers to execute JavaScript code in the victim's browser session, potentially enabling them to access and exfiltrate sensitive application data that adheres to same-origin policies. This capability undermines the fundamental security boundaries of the application, as attackers can leverage stolen session tokens or authentication contexts to perform actions such as modifying user settings, accessing private communications, or even escalating privileges within the system. The vulnerability effectively transforms any authenticated user into a potential vector for account takeover attacks.
The attack surface for this vulnerability is particularly concerning given that it affects all authenticated users within the application ecosystem, creating a scalable threat model where individual compromised accounts can serve as entry points for broader exploitation. Security controls based on the CWE-79 classification for cross-site scripting vulnerabilities demonstrate the need for comprehensive input validation and output encoding strategies that address both server-side and client-side processing layers. According to ATT&CK framework categorization under T1059.007 for JavaScript execution, this vulnerability enables attackers to leverage legitimate application functionality for malicious purposes while maintaining persistence through the stored nature of the XSS payload. The remediation strategy must focus on implementing robust server-side sanitization of user inputs, eliminating direct DOM manipulation through v-html directives, and employing proper output encoding mechanisms that prevent malicious code execution regardless of the content's origin.
Mitigation efforts should prioritize immediate implementation of input validation and sanitization at the server level before any data is persisted to the database. The application architecture must be redesigned to eliminate reliance on client-side regex-based sanitizers that can be bypassed through sophisticated obfuscation techniques. Security controls should incorporate Content Security Policy headers, implement proper output encoding for all dynamic content rendered in the browser, and establish comprehensive logging mechanisms to detect suspicious sharing activities. Additionally, the application should employ a defense-in-depth approach that includes regular security scanning of stored content and implementation of automated threat detection systems capable of identifying potentially malicious payloads before they can be executed against unsuspecting users, thereby protecting the integrity of the entire user communication ecosystem.