CVE-2026-18976 in hermes-agent
Summary
by MITRE • 08/06/2026
A vulnerability was determined in NousResearch hermes-agent up to 0.16.0. This impacts the function get_tool_definitions of the file agent/agent_init.py of the component disabled_toolsets Handler. This manipulation causes incorrect privilege assignment. The attack may be initiated remotely. The exploit has been publicly disclosed and may be utilized. The project was informed of the problem early through an issue report.
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Analysis
by VulDB Data Team • 08/06/2026
The vulnerability in NousResearch hermes-agent version 0.16.0 represents a critical security flaw within the disabled_toolsets Handler component that affects the get_tool_definitions function in agent/agent_init.py. This issue stems from improper privilege assignment mechanisms that allow unauthorized manipulation of tool definitions, potentially enabling malicious actors to elevate their privileges or access restricted functionality. The vulnerability's remote exploitability means attackers can leverage this flaw without requiring physical access to the system, making it particularly dangerous in networked environments where the agent might be exposed to external threats.
The technical implementation of this vulnerability demonstrates a failure in proper access control enforcement within the agent initialization process. When the get_tool_definitions function processes tool definitions, it appears to inadequately validate or sanitize input parameters that could be manipulated by remote attackers. This flaw likely stems from insufficient input validation and authorization checks that should normally prevent unauthorized modifications to core system components. The vulnerability's classification aligns with CWE-284 (Improper Access Control) which specifically addresses inadequate permissions and privilege management in software systems, particularly when dealing with toolset configurations that could provide access to sensitive operations.
The operational impact of this vulnerability extends beyond simple privilege escalation as it potentially allows attackers to manipulate the entire toolset configuration of the hermes-agent. This could enable malicious actors to disable security features, enable unauthorized tools, or redirect system functionality in ways that compromise overall system integrity. The fact that exploitation has been publicly disclosed increases the risk profile significantly, as threat actors can readily develop and deploy exploits without requiring advanced technical knowledge or discovery effort. The vulnerability affects the agent's ability to properly manage its own toolset definitions, creating a potential attack surface where unauthorized modifications could persist and propagate through the system.
Mitigation strategies should focus on immediate patching of the hermes-agent to version 0.16.1 or later where this vulnerability has been addressed. Organizations should implement network segmentation to limit exposure of the agent to untrusted networks and consider implementing additional monitoring for unusual toolset modifications or privilege changes. The remediation process should include thorough code review of the disabled_toolsets Handler component to ensure proper validation of all input parameters and implementation of robust access control mechanisms. Security teams should also conduct comprehensive vulnerability assessments to identify any potential exploitation attempts that may have already occurred, given the public disclosure of the exploit. Additionally, implementing principle of least privilege configurations for agent operations and regular security audits of toolset definitions will help prevent similar issues in future deployments. The ATT&CK framework categorizes this type of vulnerability under privilege escalation techniques and could be leveraged by attackers to establish persistent access or move laterally within compromised environments.
The vulnerability's discovery through an issue report indicates that the project maintains some level of community engagement and security awareness, but the delay between identification and public disclosure suggests potential gaps in the security response process. This timeline highlights the importance of rapid patch deployment and coordinated disclosure practices that minimize the window of opportunity for attackers to exploit known vulnerabilities. Organizations utilizing this agent should consider implementing additional layers of defense including runtime monitoring, anomaly detection systems, and regular penetration testing to identify similar privilege management flaws that might exist elsewhere in their software ecosystems.