CVE-2026-0755 Overview
CVE-2026-0755 is a critical command injection vulnerability affecting gemini-mcp-tool, a tool designed for model context protocol integration. This vulnerability allows remote attackers to execute arbitrary code on affected installations without requiring authentication.
The flaw exists within the implementation of the execAsync method, where improper validation of user-supplied strings enables attackers to inject malicious commands that are subsequently executed as system calls. Successful exploitation grants attackers code execution privileges in the context of the service account.
Critical Impact
Unauthenticated remote attackers can achieve arbitrary code execution on vulnerable systems, potentially leading to complete system compromise, data theft, and lateral movement within the network.
Affected Products
- gemini-mcp-tool (all versions prior to patch)
Discovery Timeline
- 2026-01-23 - CVE-2026-0755 published to NVD
- 2026-01-26 - Last updated in NVD database
Technical Details for CVE-2026-0755
Vulnerability Analysis
This vulnerability is classified as CWE-78 (Improper Neutralization of Special Elements used in an OS Command), commonly known as OS Command Injection. The execAsync method in gemini-mcp-tool fails to properly sanitize user-controlled input before incorporating it into system command execution.
When a user-supplied string is passed to execAsync, the function constructs a system call without adequate validation or escaping of shell metacharacters. This allows attackers to break out of the intended command context and inject arbitrary shell commands that execute with the privileges of the service account running gemini-mcp-tool.
The vulnerability is particularly severe because it requires no authentication, enabling any network-accessible attacker to exploit the flaw remotely. The impact spans complete confidentiality, integrity, and availability compromise of the affected system.
Root Cause
The root cause is insufficient input validation in the execAsync method implementation. The function directly incorporates user-supplied data into shell command construction without sanitizing or escaping special characters such as semicolons (;), pipes (|), command substitution sequences ($()), and other shell metacharacters that enable command chaining or injection.
Attack Vector
The attack vector is network-based, requiring no user interaction or authentication. An attacker can send a specially crafted request to the gemini-mcp-tool service containing malicious command injection payloads. The payload traverses the normal application flow until it reaches the vulnerable execAsync method, where the injected commands are executed by the underlying operating system shell.
A typical attack scenario involves embedding shell metacharacters within the user-controlled input to terminate the intended command and append malicious commands. For example, injecting command separators followed by arbitrary commands allows attackers to execute any code accessible to the service account. For detailed technical analysis, refer to the Zero Day Initiative Advisory ZDI-26-021.
Detection Methods for CVE-2026-0755
Indicators of Compromise
- Unexpected child processes spawned by the gemini-mcp-tool service process
- Unusual network connections originating from the service account
- Anomalous system commands in process logs associated with gemini-mcp-tool
- Evidence of shell metacharacters in application request logs
Detection Strategies
- Monitor process execution chains for unexpected command execution from the gemini-mcp-tool parent process
- Implement application-layer inspection to detect shell metacharacters in requests to gemini-mcp-tool endpoints
- Deploy endpoint detection rules targeting command injection patterns such as command separators and shell metacharacters in input parameters
- Review authentication logs for unauthenticated access attempts to the service
Monitoring Recommendations
- Enable verbose logging for the gemini-mcp-tool service to capture all incoming requests
- Configure SIEM alerts for process creation events involving common post-exploitation commands (e.g., whoami, id, curl, wget) spawned by the service
- Monitor outbound network traffic from systems running gemini-mcp-tool for unexpected connections
- Implement file integrity monitoring on critical system directories
How to Mitigate CVE-2026-0755
Immediate Actions Required
- Restrict network access to gemini-mcp-tool to trusted IP ranges only until a patch is available
- Implement web application firewall rules to block requests containing shell metacharacters
- Consider disabling or isolating the gemini-mcp-tool service if not business-critical
- Review service account permissions and apply the principle of least privilege
Patch Information
No vendor patch information is currently available. Monitor the Zero Day Initiative Advisory ZDI-26-021 for updates on remediation guidance. Organizations should contact the vendor directly for patch availability and timeline information.
Workarounds
- Deploy network segmentation to isolate systems running gemini-mcp-tool from untrusted networks
- Implement input validation at the network perimeter using a WAF or reverse proxy to filter shell metacharacters
- Run the gemini-mcp-tool service in a containerized or sandboxed environment to limit the impact of successful exploitation
- Disable the execAsync functionality if it is not required for operational purposes
# Example: Network isolation using iptables
# Restrict gemini-mcp-tool service access to trusted networks only
iptables -A INPUT -p tcp --dport <service_port> -s <trusted_network>/24 -j ACCEPT
iptables -A INPUT -p tcp --dport <service_port> -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
