CVE-2025-14542 in python-utcp
Summary
by MITRE • 12/13/2025
The vulnerability arises when a client fetches a tools’ JSON specification, known as a Manual, from a remote Manual Endpoint. While a provider may initially serve a benign manual (e.g., one defining an HTTP tool call), earning the clients’ trust, a malicious provider can later change the manual to exploit the client.
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Analysis
by VulDB Data Team • 12/13/2025
This vulnerability represents a sophisticated supply chain attack vector that leverages the trust relationship between clients and remote manual endpoints. The flaw exists in systems that dynamically fetch and execute tool specifications from external sources, creating a persistent risk where initially legitimate configurations can be silently compromised. The vulnerability stems from the lack of proper validation and integrity checking mechanisms when retrieving JSON specification files that define tool behaviors and capabilities. According to CWE-494, this manifests as a Download of Code Without Integrity Check, where the system fails to verify the authenticity and integrity of downloaded components. The attack exploits the principle of least privilege by allowing a malicious actor to manipulate tool definitions that clients have previously trusted, effectively creating a persistent backdoor within the client's operational environment.
The technical implementation of this vulnerability occurs when clients establish connections to remote endpoints to retrieve manual specifications that define available tools and their execution parameters. These manual files typically contain JSON structures that describe tool interfaces, input validation rules, and execution contexts. When a client fetches such a manual from a remote endpoint, it assumes the content is trustworthy based on previous interactions or initial validation. The malicious provider can later modify the manual to include unauthorized tool definitions, altered execution parameters, or even malicious payloads that exploit the client's trust in the tool specification. This creates a scenario where the client's security posture can be compromised without any explicit user interaction or awareness, as the system automatically fetches and processes the updated manual.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise and data exfiltration capabilities. Attackers can leverage this vulnerability to inject malicious tool definitions that appear legitimate to the client system, enabling them to perform unauthorized operations within the client's environment. The vulnerability allows for persistent access patterns that can bypass traditional security controls, as the malicious tool definitions are indistinguishable from legitimate ones until execution occurs. This aligns with ATT&CK technique T1555.003 for credentials from password stores and T1059.001 for command and scripting interpreter, as the compromised tools can be used to execute malicious commands or extract credentials from the client environment. The vulnerability particularly affects systems that rely on dynamic tool discovery and execution, creating a broad attack surface where multiple client configurations can be simultaneously compromised.
Mitigation strategies must focus on implementing robust integrity verification mechanisms and establishing secure communication channels for manual retrieval. Organizations should implement digital signature verification for all fetched manual specifications, ensuring that any modification to the content is immediately detected and rejected. The implementation of certificate pinning and secure transport protocols such as TLS 1.3 with proper certificate validation can prevent man-in-the-middle attacks that would otherwise allow malicious providers to intercept and modify manual content. Additionally, clients should implement a caching mechanism with version control that maintains a history of manual specifications and alerts administrators to any unauthorized changes. According to NIST SP 800-53 control CM-7, organizations must maintain configuration baselines and ensure that all changes to system components are authorized and verified. The system should also implement automated monitoring for suspicious manual modifications and establish incident response procedures that can quickly identify and isolate compromised client systems. Regular security assessments and penetration testing should verify that the integrity checking mechanisms are functioning correctly and that no bypass opportunities exist in the manual retrieval and validation processes.