CVE-2026-81835 in Roo-Code
Summary
by MITRE • 08/28/2026
A security vulnerability has been detected in RooCodeInc Roo-Code up to 3.51.1. This affects the function fetch_instructions of the file malicious_mcp_server.py of the component MCP Integration Trust Model. The manipulation leads to code injection. The attack is possible to be carried out remotely. The exploit has been disclosed publicly and may be used. Multiple isses were reported to the vendor beforehand. They explain, that "they all apply to Roo Code, a project we no longer support - the repository was archived a while ago, and we don't encourage anyone to use it." This vulnerability only affects products that are no longer supported by the maintainer.
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Analysis
by VulDB Data Team • 08/28/2026
The identified security flaw resides within the MCP Integration Trust Model of RooCodeInc Roo-Code versions up to 3.51.1, specifically targeting the fetch_instructions function located in the malicious_mcp_server.py file. This vulnerability represents a critical failure in input validation and sanitization mechanisms, allowing for remote code injection attacks. The core technical issue stems from the application's handling of external instructions or commands fetched during its operation, where user-supplied data is processed without adequate checks against executable payloads. When an attacker manipulates these inputs, they can inject malicious code that executes within the context of the running application, effectively bypassing intended security boundaries and gaining unauthorized control over system resources.
From a technical perspective, this vulnerability aligns with CWE-94 Improper Control of Generation of Code or Script, commonly known as code injection. The flaw allows an attacker to dictate the execution flow by injecting arbitrary commands that are interpreted and executed by the underlying environment. This type of exploitation is particularly dangerous because it can lead to full system compromise, data exfiltration, or the establishment of persistent backdoors depending on the privileges held by the application process. The presence of a file named malicious_mcp_server.py suggests that this component may have been designed for testing or simulation purposes but was inadvertently included in production builds without sufficient hardening against adversarial inputs.
The operational impact of this vulnerability is severe due to its remote exploitability. An attacker does not need physical access or prior authentication within the application's internal logic if network exposure exists, making it a high-risk vector for automated attacks. Successful exploitation could result in unauthorized data access, modification of system configurations, or complete takeover of the host environment. Given that Roo-Code is an archived project no longer supported by its maintainer, there are no security patches available to remediate this issue. Users relying on these older versions face persistent exposure to known attack techniques without any possibility of vendor-provided fixes.
Mitigation strategies for organizations still operating with legacy software must focus on compensating controls since patching is not an option. Network segmentation should be implemented to restrict access to systems running the vulnerable version, ensuring that only trusted IP addresses can interact with the service. Additionally, deploying Web Application Firewalls or intrusion detection systems configured to detect code injection patterns in HTTP requests and API calls can help block exploitation attempts at the network perimeter. Input validation logic must also be reviewed manually if source code is available, though given the archived status of the repository, this may not be feasible for most users. The primary recommendation remains to migrate away from unsupported software immediately to eliminate the attack surface entirely.
This incident highlights the risks associated with maintaining dependencies on abandoned projects within critical infrastructure or development environments. Industry standards such as MITRE ATT&CK classify code injection techniques under T1059 Command and Scripting Interpreter, emphasizing the need for strict monitoring of command execution events. Security teams should audit their software inventory regularly to identify end-of-life products and prioritize replacement with actively maintained alternatives that receive regular security updates and vulnerability disclosures.