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Response snapshot Oct 26, 2026, 23:07 UTC

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VulnerabilityCVE-2026-111764

A2A Java SDK has a fail-open default task authorization

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._ ---

At a glance

Exploited
Not known
Severity
7.5 High (CVSS 3.1)
Chance of exploitation
0.6% in the next 30 days
Sources
2 independent sources

What to do

GitHub lists first patched versions: org.a2aproject.sdk:a2a-java-sdk-server-common: 1.3.0.Final. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-qw47-mcm5-934w (opens a new tab)

What happened

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)

Continue reading

---

## 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:

```java 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):

1. Construct the default store: `InMemoryTaskStore store = new InMemoryTaskStore();` (no-arg constructor, so no authorization provider). 2. As one caller, save a task: `store.save(victimTask, false);` with id `victim-task-42`. 3. 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

Affected package ranges reported by GitHub: org.a2aproject.sdk:a2a-java-sdk-server-common: < 1.3.0.Final

Scores and how they were measured

CVSS base severity

7.5

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.6%

Scored Percentile 48.6%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-qw47-mcm5-934w (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qw47-mcm5-934w, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qw47-mcm5-934w, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  4. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qw47-mcm5-934w, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  5. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qw47-mcm5-934w, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  6. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qw47-mcm5-934w, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  7. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qw47-mcm5-934w, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  8. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qw47-mcm5-934w, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  9. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qw47-mcm5-934w, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  10. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qw47-mcm5-934w, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  11. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-qw47-mcm5-934w, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  12. Primary source

    NVD CVE-2026-111764 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  13. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  14. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-111764, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 20). A2A Java SDK has a fail-open default task authorization (CVE-2026-111764). https://kevwire.com/record/CVE-2026-111764

MLA

"A2A Java SDK has a fail-open default task authorization (CVE-2026-111764)." KEVWire, 20 Oct. 2026, kevwire.com/record/CVE-2026-111764.

Chicago

KEVWire. "A2A Java SDK has a fail-open default task authorization (CVE-2026-111764)." Last modified October 20, 2026. https://kevwire.com/record/CVE-2026-111764.

Evidence summary (plain text)

A2A Java SDK has a fail-open default task authorization (Oct 20, 2026).
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._

---
CVSS 7.5 (version 3.1; evidence as of Oct 20, 2026; https://github.com/advisories/GHSA-qw47-mcm5-934w).
EPSS 0.6% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-111764&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-qw47-mcm5-934w: https://github.com/advisories/GHSA-qw47-mcm5-934w
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQxNTo1Mjo1NlrOAAfxiA%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQxNDowNjoxNFrOAAfxZw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQwODoyNzoyM1rOAAYp9A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozNTo1OFrOAAfwCQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozMDoxM1rOAAfv2A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyODowOVrOAAfv1g%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyNDoyMFrOAAfv1Q%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDo0NTowN1rOAAfvzQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDozMDoyNlrOAAfvxw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDowMzo1N1rOAAfvxQ%3D%3D
NVD CVE-2026-111764: https://nvd.nist.gov/vuln/detail/CVE-2026-111764
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?pubStartDate=2026-10-12T13:35:55.142Z&pubEndDate=2026-10-26T13:35:55.142Z&resultsPerPage=500&startIndex=6000
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-111764&date=2026-10-26
Record ID: CVE-2026-111764.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 26, 2026, 19:40 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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