CVE-2026-111764
Received Received - Intake

A2A Java SDK Task Read Authorization Bypass

Publication date: 2026-10-20

Last updated on: 2026-10-20

Assigner: GitHub, Inc.

Description
A2A Java SDK is the official Java SDK for the Agent2Agent (A2A) Protocol. Prior to 1.3.0.Final, the default InMemoryTaskStore configuration performs no authorization on task reads: the no-argument constructor sets authorizationProvider to null, and InMemoryTaskStore.get(String taskId) returns the stored task without checking the caller or owner. Authorization depends on supplying a TaskAuthorizationProvider and routing requests through AuthorizationRequestHandlerDecorator, whether installed through CDI or explicitly by the application. Default store wiring and manually constructed DefaultRequestHandler.builder().build() handlers, including integrations such as Spring, leave task reads unprotected when no effective authorization-provider and decorator check is installed. In a multi-caller deployment using the default configuration, a caller who knows or guesses another caller's task ID can retrieve the task status, context ID, message history, and artifacts. The default/reference transport endpoints do not enforce authentication, so the task-read disclosure is reachable by an unauthenticated caller rather than requiring a privileged account. This issue is fixed in version 1.3.0.Final.

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Meta Information

Published
2026-10-20
Last Modified
2026-10-20
Generated
2026-10-20
AI Q&A
2026-10-20
EPSS Evaluated
N/A
NVD
CVE-2026-111764
EUVD
EUVD-2026-105130

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
a2aproject a2a-java < 1.3.0.Final

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-862 The product does not perform an authorization check when an actor attempts to access a resource or perform an action.
CWE-1188 The product initializes or sets a resource with a default that is intended to be changed by the product's installer, administrator, or maintainer, but the default is not secure.

Attack-Flow Graph

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Executive Summary

CVE-2026-111764 is a vulnerability in the A2A Java SDK versions 1.2.0.Final and earlier. It involves a default insecure configuration in the InMemoryTaskStore class where task reads are not authorized by default. This allows any caller with a task ID to retrieve another caller's task data, including sensitive information like status, context, message history, and artifacts, without authentication. The issue occurs because the authorizationProvider is set to null by default and the get method performs no ownership checks.

Detection Guidance

To detect this vulnerability, check if your A2A Java SDK version is 1.2.0.Final or earlier. Use commands like 'mvn dependency:tree' to inspect dependencies or check the SDK version in your project files. Verify if task reads are unprotected by default by examining the InMemoryTaskStore configuration and absence of TaskAuthorizationProvider.

Impact Analysis

In a multi-caller deployment using the default configuration, an attacker who knows or guesses a task ID can access another user's task data without authentication. This could lead to unauthorized disclosure of sensitive information such as task status, context details, message history, and attached artifacts. The impact is high due to the potential for confidentiality breaches in systems handling multiple users.

Compliance Impact

This vulnerability could lead to non-compliance with data protection regulations like GDPR and HIPAA by enabling unauthorized access to sensitive personal or health information stored in tasks. GDPR requires protecting personal data and ensuring confidentiality, while HIPAA mandates safeguards for protected health information. The lack of default authorization controls increases the risk of data breaches, potentially resulting in regulatory penalties and loss of trust.

Mitigation Strategies

Upgrade to A2A Java SDK version 1.3.0.Final or later. If upgrading is not possible, configure a TaskAuthorizationProvider and ensure requests are routed through AuthorizationRequestHandlerDecorator. Alternatively, set a2a.authorization.required=false to restore open behavior temporarily.

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