{"id":"GHSA-qw47-mcm5-934w","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\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`'s 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's 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's 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's 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's `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","aliases":["CVE-2026-111764"],"modified":"2026-10-20T21:15:04.046382128Z","published":"2026-10-20T21:05:09Z","database_specific":{"nvd_published_at":"2026-10-20T16:17:00Z","cwe_ids":["CWE-1188","CWE-862"],"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"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"}],"affected":[{"package":{"name":"org.a2aproject.sdk:a2a-java-sdk-server-common","ecosystem":"Maven","purl":"pkg:maven/org.a2aproject.sdk/a2a-java-sdk-server-common"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.3.0.Final"}]}],"versions":["1.0.0.Alpha4","1.0.0.Beta1","1.0.0.CR1","1.0.0.Final","1.1.0.Final","1.2.0.Final"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-qw47-mcm5-934w/GHSA-qw47-mcm5-934w.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"}]}