CVE-2026-111764: CWE-862: Missing Authorization in a2aproject a2a-java

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: ```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