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TI-2026-76904 Aliases CVE-2026-111764GHSA-qw47-mcm5-934w

A2A Java SDK default task store skips authorization on task reads

Priority HIGH 72CWE-1188Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-862.

Summary

The A2A Java SDK from a2aproject, before 1.3.0.Final, has an insecure default in its InMemoryTaskStore, which performs no authorization on task reads (CWE-1188, CWE-862). In a multi-caller deployment using the default configuration, an unauthenticated remote caller who knows or guesses another caller's task ID can retrieve that task's status, context ID, message history and artifacts. The transport endpoints do not require authentication.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00604 49th percentileScored 2026-11-07
Fix Fixed a2a-java (a2aproject): 1.3.0.Finalorg.a2aproject.sdk:a2a-java-sdk-server-common (Maven): 1.3.0.Final

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
a2aprojecta2a-javabefore 1.3.0.Final1.3.0.FinalPatch availableCNA
—org.a2aproject.sdk:a2a-java-sdk-server-common (Maven)before 1.3.0.Final1.3.0.FinalPatch availableGHSA-qw47-mcm5-934w
  • a2a-java Vendora2aproject Affected before 1.3.0.Final Fixed in 1.3.0.Final Patch available CNA
  • org.a2aproject.sdk:a2a-java-sdk-server-common (Maven) Vendor— Affected before 1.3.0.Final Fixed in 1.3.0.Final Patch available GHSA-qw47-mcm5-934w

Remediation

Upgrade org.a2aproject.sdk:a2a-java-sdk-server-common to 1.3.0.Final. The sources list no fixed version for a2a-java. Until upgraded, install a TaskAuthorizationProvider and route requests through AuthorizationRequestHandlerDecorator.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

  • Fix · CNA a2a-java (a2aproject) Fixed in 1.3.0.Final
  • Fix · GHSA-qw47-mcm5-934w org.a2aproject.sdk:a2a-java-sdk-server-common (Maven) Fixed in 1.3.0.Final Advisory →

Timeline

  1. 2026-10-20 Threatist record created from CVE-2026-111764
  2. 2026-10-20 CISA SSVC decision points changed
  3. 2026-10-20 Priority changed: MEDIUM → HIGH
  4. 2026-10-21 Alias added: GHSA-qw47-mcm5-934w
  5. 2026-10-21 Fix available: Maven/org.a2aproject.sdk:[email protected] · GHSA-qw47-mcm5-934w
  6. 2026-10-21 CVSS score added · GHSA-qw47-mcm5-934w
  7. 2026-10-21 Weakness changed · GHSA-qw47-mcm5-934w
  8. 2026-10-21 6 new references · GHSA-qw47-mcm5-934w

References

Advisory 1

Other 5

  • TI-2026-76905 Android A2A Java SDK forwards API keys across redirects CVSS 3.1HIGH 7.5
  • TI-2026-76847 Server-side request forgery in A2A Java SDK push notifications CVSS 3.1MEDIUM 5.8
  • TI-2026-81183 Resource consumption in a2aproject a2a-go REST SSE handler CVSS 4.0MEDIUM 6.9
  • TI-2026-61722 HTTP response splitting in a2aproject a2a-java CVSS 4.0MEDIUM 6.9
  • TI-2026-81185 Denial of service in a2aproject a2a-go Distributed Manager Cancel CVSS 4.0MEDIUM 6.9
  • TI-2026-80567 Error message leaks sensitive information in a2a-go CreateExecutor CVSS 4.0MEDIUM 6.9
See all 21 →

Sources

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