CVE-2026-116479 in a2a-java
Summary
by MITRE • 10/26/2026
A flaw has been found in a2aproject a2a-java up to 1.2.0.Final. This impacts the function getMessage of the component JSON-RPC Error Handler. This manipulation causes information exposure through error message. The attack can be initiated remotely. Upgrading to version 1.3.0.Final will fix this issue. Patch name: bbee3369f3825d0fba2373d821f6dc6d4fc82ec0. Upgrading the affected component is advised.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 10/26/2026
The a2a-java library, specifically versions up to 1.2.0.Final of the A2A project, contains a critical information disclosure vulnerability within its JSON-RPC error handling mechanism. This flaw resides in the getMessage function, which is responsible for formatting and returning error details when an exception occurs during the processing of JSON-RPC requests. The core technical issue stems from insufficient sanitization or filtering of internal application state before it is included in the response payload sent back to the client. When a server-side error triggers this handler, instead of returning a generic, user-friendly message, the component exposes raw stack traces, internal variable values, database query details, or other sensitive contextual data that was intended only for developer debugging purposes. This behavior violates fundamental security principles regarding the separation of debug information from production outputs and represents a classic case of improper error handling leading to unauthorized access to system internals.
From an operational perspective, this vulnerability allows remote attackers to gather significant intelligence about the target environment without needing prior authentication or specific exploit code beyond triggering an error condition. By sending malformed requests or inducing failures in various endpoints handled by the JSON-RPC interface, an attacker can systematically probe the application for weaknesses. The exposed information may reveal file paths, library versions, database schemas, and internal logic flows that are invaluable during the reconnaissance phase of a cyber attack. This data enables attackers to craft more precise exploits against known vulnerabilities in specific dependencies or to identify logical flaws within the business logic. Consequently, this flaw significantly lowers the barrier for subsequent attacks such as SQL injection, remote code execution, or privilege escalation, as it provides the attacker with a detailed map of the application's architecture and potential weak points.
This vulnerability aligns closely with Common Weakness Enumeration (CWE) category CWE-209: Generation of Error Message Containing Sensitive Information, which classifies flaws where software generates error messages that include sensitive information about its internal state or configuration. It also relates to CWE-755: Improper Handling of Unexpected Data Condition, as the system fails to gracefully handle unexpected inputs by masking internal details. In terms of the MITRE ATT&CK framework, this flaw facilitates the Information Gathering technique (T1059), specifically through command and script interpretation or API abuse depending on how the JSON-RPC endpoint is accessed. The exposure aids adversaries in mapping network topology and identifying entry points for further exploitation, thereby increasing the overall risk profile of any service relying on these affected versions of a2a-java.
To mitigate this vulnerability, organizations must immediately upgrade the a2a-java dependency to version 1.3.0.Final or later, where the patch identified by commit hash bbee3369f3825d0fba2373d821f6dc6d4fc82ec0 addresses the issue by ensuring that error messages are sanitized and do not leak internal state details. In addition to upgrading, developers should implement a centralized exception handling strategy across all JSON-RPC endpoints to ensure consistent masking of technical errors for end-users while logging detailed stack traces securely on the server side only. It is also recommended to conduct a thorough review of other components within the application that might exhibit similar behaviors, ensuring that no other error handlers inadvertently expose sensitive data. Regular security testing and static code analysis should be integrated into the development lifecycle to detect such information leakage patterns early before they reach production environments.