CVE-2026-111764 A2A Java SDK has a fail-open default task authorization

What is CVE-2026-111764?

CVE-2026-111764 is a high-severity vulnerability in a2aproject a2a-java, published on 20 Oct 2026.

Official 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.

Weakness: CWE-862, CWE-1188

Which versions are affected by CVE-2026-111764?

2 open source packages ship an affected version, including org.a2aproject.sdk:a2a-java-sdk-server-common.

How do I fix CVE-2026-111764?

Upgrade org.a2aproject.sdk:a2a-java-sdk-server-common to 1.3.0.Final or later.

Is CVE-2026-111764 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-111764 exists.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-qw47-mcm5-934w.