CVE-2026-116477 in a2a-dotnet
Summary
by MITRE • 10/26/2026
A security vulnerability has been detected in a2aproject a2a-dotnet up to 1.0.0-preview2. The impacted element is the function A2AJsonRpcProcessor.ProcessRequestAsync of the file src/A2A.AspNetCore/A2AJsonRpcProcessor.cs of the component Parser. The manipulation leads to information exposure through error message. It is possible to initiate the attack remotely. Upgrading to version 1.0.0-preview3 is sufficient to resolve this issue. The identifier of the patch is ccbd12b6108a6a8f0fd5d8b4a9ece3c8a94ba1e4. Upgrading the affected component is recommended.
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Analysis
by VulDB Data Team • 10/26/2026
The a2aproject, specifically within its dotnet implementation up to version 1.0.0-preview2, contains a security vulnerability in the A2AJsonRpcProcessor.ProcessRequestAsync function located in src/A2A.AspNetCore/A2AJsonRpcProcessor.cs. This component is responsible for parsing and processing JSON-RPC requests within the ASP.NET Core environment. The flaw arises from inadequate sanitization or filtering of error messages generated during request processing, which can inadvertently expose sensitive internal information to external parties.
This vulnerability falls under the category of Information Exposure through Error Messages, commonly classified as CWE-209 in the Common Weakness Enumeration framework. When an attacker sends a malformed or maliciously crafted JSON-RPC request, the application may throw an exception that is not properly handled. Instead of returning a generic error message to the client, the system leaks detailed stack traces, internal file paths, database connection strings, or other configuration details embedded in the raw exception output. This behavior provides attackers with valuable intelligence about the underlying technology stack and architecture.
The operational impact of this vulnerability allows for remote information disclosure without requiring authentication. An attacker can initiate the attack from a remote location by sending specific HTTP requests to the affected endpoint. The exposure of internal error messages facilitates further reconnaissance, enabling adversaries to identify vulnerable libraries, operating system details, or application logic flaws that could be exploited in subsequent attacks such as SQL injection, path traversal, or privilege escalation. This significantly lowers the barrier for entry and increases the risk profile of the deployed service.
The vulnerability was addressed in version 1.0.0-preview3 through patch identifier ccbd12b6108a6a8f0fd5d8b4a9ece3c8a94ba1e4. The fix likely involves implementing robust exception handling mechanisms that catch specific errors and return standardized, non-revealing error responses to the client while logging detailed information securely on the server side only. This aligns with security best practices outlined in OWASP guidelines for preventing information leakage via HTTP responses.
To mitigate this risk immediately, organizations should upgrade the a2a-dotnet component to version 1.0.0-preview3 or later as soon as possible. In environments where upgrading is not immediately feasible, temporary mitigations include configuring custom error pages in ASP.NET Core to suppress detailed exception details for remote users and ensuring that logging levels are set appropriately so that sensitive data is never written to logs accessible by unauthorized parties. Additionally, implementing Web Application Firewall rules can help detect and block malformed JSON-RPC requests before they reach the application logic, providing an additional layer of defense against exploitation attempts.