CVE-2026-111761 A2A Java SDK has Server-Side Request Forgery (SSRF) in push-notification delivery
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-111761?
CVE-2026-111761 is a medium-severity vulnerability in a2aproject a2a-java, published on 20 Oct 2026.
Official description
A2A Java SDK is the official Java SDK for the Agent2Agent (A2A) Protocol. Prior to 1.3.0.Final, BasePushNotificationSender in server-common sends task data to the URL in TaskPushNotificationConfig without destination validation, scheme restrictions, or bounds on redirects. InMemoryPushNotificationConfigStore.setInfo stores the URL verbatim, and onCreateTaskPushNotificationConfig does not validate the destination. In the default deployment with push notifications enabled, an unauthenticated caller can register a destination through an inline SendMessage configuration or CreateTaskPushNotificationConfig for an existing task, causing task status and artifact updates to send requests from the server's network position to loopback, private, link-local cloud-metadata, IPv6 unique-local, unspecified, or multicast destinations where routing permits. JdkA2AHttpClient and VertxA2AHttpClient follow redirects, allowing a webhook redirect to bypass creation-time destination checks and convert a POST into a GET; hostname-only checks also do not prevent DNS rebinding. Direct POST delivery can push attacker-influenced task data into internal services, whereas a redirected POST-to-GET request drops the body. The sender discards the fetched response and does not expose delivery success or failure, so the demonstrated behavior does not provide response read-back. No credentials or user interaction are required. This issue is fixed in version 1.3.0.Final.
Weakness: CWE-918
Which versions are affected by CVE-2026-111761?
2 open source packages ship an affected version, including org.a2aproject.sdk:a2a-java-sdk-server-common.
| Package | Affected | Fixed in |
|---|---|---|
org.a2aproject.sdk:a2a-java-sdk-server-common Maven | All versions | 1.3.0.Final |
org.a2aproject.sdk:a2a-java-sdk-server-common Maven | All versions | 1.3.0.Final |
How do I fix CVE-2026-111761?
Upgrade org.a2aproject.sdk:a2a-java-sdk-server-common to 1.3.0.Final or later.
Is CVE-2026-111761 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-111761 exists.
Sources
Also known as GHSA-q78c-5jjq-57g8.