Vulnerability-Lookup

CVE-2026-111764 (GCVE-0-2026-111764)

Vulnerability from cvelistv5 – Published: 2026-10-20 15:05 – Updated: 2026-10-20 16:15

Title

A2A Java SDK has a fail-open default task authorization

Summary

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.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-20 16:15 UTC

CWE

CWE-862 - Missing Authorization
CWE-1188 - Insecure Default Initialization of Resource

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7639 records in the last 180 days details

References

4 references

URL	Tags
https://github.com/a2aproject/a2a-java/security/a…	x_refsource_CONFIRM
https://github.com/a2aproject/a2a-java/pull/1095	x_refsource_MISC
https://github.com/a2aproject/a2a-java/commit/efb…	x_refsource_MISC
https://github.com/a2aproject/a2a-java/releases/t…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
a2aproject	a2a-java	Affected: < 1.3.0.Final	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-111764

Vulnerability from fkie_nvd - Published: 2026-10-20 16:17 - Updated: 2026-10-20 19:56

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/a2aproject/a2a-java/commit/efb4e985e99390c4fc1f78c0a187a4254c0a2553
	security-advisories@github.com	https://github.com/a2aproject/a2a-java/pull/1095
	security-advisories@github.com	https://github.com/a2aproject/a2a-java/releases/tag/v1.3.0.Final
	security-advisories@github.com	https://github.com/a2aproject/a2a-java/security/advisories/GHSA-qw47-mcm5-934w
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/a2aproject/a2a-java/security/advisories/GHSA-qw47-mcm5-934w

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
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  ],
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  "lastModified": "2026-10-20T19:56:45.543",
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}

GHSA-QW47-MCM5-934W

Vulnerability from github – Published: 2026-10-20 21:05 – Updated: 2026-10-20 21:05

Summary

A2A Java SDK has a fail-open default task authorization

Details

Draft text for GHSA-qw47-mcm5-934w. The body below drops into the GitHub advisory description field; the metadata block maps to the form fields. Set the patched version at release; publish when the fix ships._

Ecosystem: Maven
Affected package: org.a2aproject.sdk:a2a-java-sdk-server-common (task store / authorization)
Affected versions: <= 1.2.0.Final (and 1.2.1.Final-SNAPSHOT on main prior to the fix)
Patched version: (the release that carries the fix, e.g. 1.2.1.Final)
CWE: CWE-1188 (Insecure Default Initialization), CWE-862 (Missing Authorization)
Severity: High
CVSS v3.1: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N (7.5, High)

Details

The default task store performs no authorization on task reads. InMemoryTaskStore's no-arg constructor sets authorizationProvider = null, and InMemoryTaskStore.get(String taskId) is a bare map lookup with no authorization check regardless of provider:

public InMemoryTaskStore() {
    this.authorizationProvider = null;   // default wiring
}

@Override
public @Nullable Task get(String taskId) {
    return tasks.get(taskId);            // no owner / caller check
}

Authorization is enforced only when the application both supplies a TaskAuthorizationProvider and routes requests through AuthorizationRequestHandlerDecorator (via CDI), which checks ownership before delegating. A server that uses the default store, or wires DefaultRequestHandler.builder().build() manually, or integrates through a non-CDI stack (e.g. Spring), never reaches that check. The safe posture is therefore opt-in and the shipped default is the unsafe one. A caller can read a task created by another caller simply by knowing or guessing its id.

Summary

With the SDK's default configuration, task reads are not authorized: any caller can retrieve a task (including its status, context, message history, and artifacts) created by another caller, by supplying the task id.

PoC

Using only the real production classes wired the default way (no mocks):

Construct the default store: InMemoryTaskStore store = new InMemoryTaskStore(); (no-arg constructor, so no authorization provider).
As one caller, save a task: store.save(victimTask, false); with id victim-task-42.
As a second, unrelated caller with no auth context, read it back: store.get("victim-task-42").

The second caller receives the first caller's task in full, with no authorization check:

unauthenticated get(victim-task-42) returned task owned by nobody-checked: victim-task-42 / ctx=victim-ctx

Verified on main (commit 72d220c, JDK 21) and reproduces unchanged on 1.2.0.Final.

Impact

Task data crosses caller boundaries with no authorization. In any multi-caller deployment built on the default wiring, one caller can enumerate and read another caller's tasks, including task status, context id, the message history, and any artifacts the task carries, which for agent workloads is frequently sensitive input and generated content. Because the insecure behaviour is the default rather than a misconfiguration, it is easy to ship unintentionally, and in the default/reference deployment the transport endpoints are served without authentication enforced, so the read is reachable by an unauthenticated caller (PR:N). CVSS is scored against the default configuration as shipped.

Remediation

Fail closed by default: deny task reads when no authorization provider is configured, rather than treating a missing provider as allow-all, and apply the authorization check in the store's get path (not only in list and the CDI decorator) so it holds regardless of how the handler is wired. If the current permissive default is retained for single-user/testing scenarios, emit a prominent startup warning when the server comes up with no authorization provider so it cannot be shipped by accident.

Workarounds

Until a fixed release, configure a TaskAuthorizationProvider and ensure requests are routed through the authorization decorator (CDI wiring), rather than relying on the default no-arg store or a manually built handler.

References

CWE-1188: Insecure Default Initialization of Resource: https://cwe.mitre.org/data/definitions/1188.html
CWE-862: Missing Authorization: https://cwe.mitre.org/data/definitions/862.html

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "org.a2aproject.sdk:a2a-java-sdk-server-common"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.3.0.Final"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-111764"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1188",
      "CWE-862"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-20T21:05:09Z",
    "nvd_published_at": "2026-10-20T16:17:00Z",
    "severity": "HIGH"
  },
  "details": "Draft text for GHSA-qw47-mcm5-934w. The body below drops into the GitHub advisory description\nfield; the metadata block maps to the form fields. Set the patched version at release; publish\nwhen the fix ships._\n\n---\n\n- **Ecosystem:** Maven\n- **Affected package:** `org.a2aproject.sdk:a2a-java-sdk-server-common` (task store / authorization)\n- **Affected versions:** `\u003c= 1.2.0.Final` (and `1.2.1.Final-SNAPSHOT` on `main` prior to the fix)\n- **Patched version:** _(the release that carries the fix, e.g. 1.2.1.Final)_\n- **CWE:** CWE-1188 (Insecure Default Initialization), CWE-862 (Missing Authorization)\n- **Severity:** High\n- **CVSS v3.1:** `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N` (7.5, High)\n\n---\n\n## Details\n\nThe default task store performs no authorization on task reads. `InMemoryTaskStore`\u0027s no-arg\nconstructor sets `authorizationProvider = null`, and `InMemoryTaskStore.get(String taskId)` is a\nbare map lookup with no authorization check regardless of provider:\n\n```java\npublic InMemoryTaskStore() {\n    this.authorizationProvider = null;   // default wiring\n}\n\n@Override\npublic @Nullable Task get(String taskId) {\n    return tasks.get(taskId);            // no owner / caller check\n}\n```\n\nAuthorization is enforced only when the application both supplies a `TaskAuthorizationProvider`\n*and* routes requests through `AuthorizationRequestHandlerDecorator` (via CDI), which checks\nownership before delegating. A server that uses the default store, or wires\n`DefaultRequestHandler.builder().build()` manually, or integrates through a non-CDI stack (e.g.\nSpring), never reaches that check. The safe posture is therefore opt-in and the shipped default is\nthe unsafe one. A caller can read a task created by another caller simply by knowing or guessing\nits id.\n\n## Summary\n\nWith the SDK\u0027s default configuration, task reads are not authorized: any caller can retrieve a\ntask (including its status, context, message history, and artifacts) created by another caller,\nby supplying the task id.\n\n## PoC\n\nUsing only the real production classes wired the default way (no mocks):\n\n1. Construct the default store: `InMemoryTaskStore store = new InMemoryTaskStore();` (no-arg\n   constructor, so no authorization provider).\n2. As one caller, save a task: `store.save(victimTask, false);` with id `victim-task-42`.\n3. As a second, unrelated caller with no auth context, read it back: `store.get(\"victim-task-42\")`.\n\nThe second caller receives the first caller\u0027s task in full, with no authorization check:\n\n```\nunauthenticated get(victim-task-42) returned task owned by nobody-checked: victim-task-42 / ctx=victim-ctx\n```\n\nVerified on `main` (commit `72d220c`, JDK 21) and reproduces unchanged on `1.2.0.Final`.\n\n## Impact\n\nTask data crosses caller boundaries with no authorization. In any multi-caller deployment built on\nthe default wiring, one caller can enumerate and read another caller\u0027s tasks, including task status,\ncontext id, the message history, and any artifacts the task carries, which for agent workloads is\nfrequently sensitive input and generated content. Because the insecure behaviour is the default\nrather than a misconfiguration, it is easy to ship unintentionally, and in the default/reference\ndeployment the transport endpoints are served without authentication enforced, so the read is\nreachable by an unauthenticated caller (`PR:N`). CVSS is scored against the default configuration\nas shipped.\n\n## Remediation\n\nFail closed by default: deny task reads when no authorization provider is configured, rather than\ntreating a missing provider as allow-all, and apply the authorization check in the store\u0027s `get`\npath (not only in `list` and the CDI decorator) so it holds regardless of how the handler is\nwired. If the current permissive default is retained for single-user/testing scenarios, emit a\nprominent startup warning when the server comes up with no authorization provider so it cannot be\nshipped by accident.\n\n## Workarounds\n\nUntil a fixed release, configure a `TaskAuthorizationProvider` and ensure requests are routed\nthrough the authorization decorator (CDI wiring), rather than relying on the default no-arg store\nor a manually built handler.\n\n## References\n\n- CWE-1188: Insecure Default Initialization of Resource: https://cwe.mitre.org/data/definitions/1188.html\n- CWE-862: Missing Authorization: https://cwe.mitre.org/data/definitions/862.html",
  "id": "GHSA-qw47-mcm5-934w",
  "modified": "2026-10-20T21:05:09Z",
  "published": "2026-10-20T21:05:09Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/a2aproject/a2a-java/security/advisories/GHSA-qw47-mcm5-934w"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-111764"
    },
    {
      "type": "WEB",
      "url": "https://github.com/a2aproject/a2a-java/pull/1095"
    },
    {
      "type": "WEB",
      "url": "https://github.com/a2aproject/a2a-java/commit/efb4e985e99390c4fc1f78c0a187a4254c0a2553"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/a2aproject/a2a-java"
    },
    {
      "type": "WEB",
      "url": "https://github.com/a2aproject/a2a-java/releases/tag/v1.3.0.Final"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "A2A Java SDK has a fail-open default task authorization"
}

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CVE-2026-111764 (GCVE-0-2026-111764)

FKIE_CVE-2026-111764

GHSA-QW47-MCM5-934W

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