CVE-2025-40896 in Arc
Summary
by MITRE • 03/04/2026
The server certificate was not verified when an Arc agent connected to a Guardian or CMC.
A malicious actor could perform a man-in-the-middle attack and intercept the communication between the Arc agent and the Guardian or CMC. This could result in theft of the client token and sensitive information (such as assets and alerts), impersonation of the server, or injection of spoofed data (such as false asset information or vulnerabilities) into the Guardian or CMC.
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Analysis
by VulDB Data Team • 03/06/2026
The vulnerability identified as CVE-2025-40896 represents a critical security flaw in the certificate verification process of Arc agent communications with Guardian or CMC systems. This weakness occurs when an Arc agent establishes a connection to either a Guardian or CMC server, failing to properly validate the server certificate presented during the TLS handshake process. The absence of certificate verification creates a fundamental breach in the authentication framework that protects sensitive communications between these components. This vulnerability directly violates industry standards such as CWE-295 which specifically addresses improper certificate validation and authentication failures in secure communications. The flaw essentially removes the cryptographic assurance that the agent is communicating with the legitimate server rather than an attacker-controlled intermediary.
The operational impact of this vulnerability extends far beyond simple communication issues, creating multiple attack vectors for malicious actors seeking to compromise the system. When certificate verification is disabled or bypassed, attackers can successfully execute man-in-the-middle attacks by positioning themselves between the Arc agent and the target server. This allows them to intercept, modify, or steal all transmitted data including sensitive client tokens that grant access to protected resources. The compromised communication channel enables attackers to impersonate legitimate servers, effectively allowing them to assume the identity of authorized systems within the network. This impersonation capability provides attackers with elevated privileges and access to confidential information that should remain protected.
The potential consequences of exploiting this vulnerability include comprehensive data theft and system compromise. Attackers can extract client tokens which provide unauthorized access to enterprise resources, potentially enabling them to access sensitive assets, alerts, and other critical operational data. The ability to inject spoofed data into Guardian or CMC systems presents additional risks where false asset information or fabricated vulnerability reports can be introduced, potentially causing security teams to make incorrect operational decisions or waste resources investigating non-existent threats. This data manipulation capability can also be used to establish persistent backdoors or to cover malicious activities by creating false audit trails. The vulnerability essentially undermines the integrity and authenticity guarantees that secure communication protocols are designed to provide, making it particularly dangerous in environments where security monitoring and incident response systems rely on accurate data flow.
Organizations should implement immediate mitigations to address this vulnerability by ensuring proper certificate verification is enforced during Arc agent connections to Guardian or CMC systems. The recommended approach involves configuring the Arc agent software to require valid certificate chains and implementing strict certificate validation policies that align with industry best practices for secure communications. System administrators should also consider implementing network-level protections such as certificate pinning to prevent attackers from substituting valid certificates with malicious ones. Regular security audits should verify that certificate validation mechanisms are properly configured and functioning as intended. Additionally, monitoring systems should be enhanced to detect anomalous communication patterns that might indicate man-in-the-middle attacks. The remediation efforts should follow established security frameworks such as those outlined in the NIST Cybersecurity Framework and should incorporate principles from the MITRE ATT&CK framework, particularly focusing on defending against initial access and credential access techniques that leverage certificate validation failures.