CVE-2026-111763
MediumCVSS 5.7Summary
A2A Java SDK prior to 1.3.0.Final allows a malicious or compromised remote agent to cause the default JDK-based client to forward a configured API key to a third-party server. AuthInterceptor uses APIKeySecurityScheme.name() from the remote AgentCard as the HTTP header name without checking that the declared location is HEADER, and JdkA2AHttpClient uses followRedirects(NORMAL), so an agent-controlled cross-origin redirect forwards the credential-bearing header.
Risk Assessment
An API key configured for the agent may be disclosed to a third party, potentially leading to unauthorized access to services. The risk affects client applications using A2A Java SDK with configured API key credentials.
Recommendation
Update A2A Java SDK to version 1.3.0.Final or later. Avoid configuring API keys for untrusted agents and consider restricting redirects.
Other vulnerabilities in A2A Java SDK
See all- CVE-2026-111765High
A2A Java SDK from 1.3.0.Final before 1.3.2.Final: the AndroidA2AHttpClient synchronous POST path overrides the disabled-redirect setting with PostBuilder's followRedirects=true. JSONRPCTransport and RestTransport add interceptor-produced authentication headers and call synchronous post() without disabling redirects, disclosing a configured API key or token to another authority on redirect.
- CVE-2026-111764High
A2A Java SDK 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 get(String taskId) returns the stored task without checking caller or owner. In a multi-caller deployment, a caller who knows another caller's task ID can retrieve task status, context ID, message history, and artifacts; default transport endpoints do not enforce authentication.
- CVE-2026-111762Medium
A2A Java SDK before 1.3.0.Final has a vulnerability in RestHandler.parseRequestBody that logs the entire JSON request body at SEVERE level when protobuf parsing fails. With push notifications enabled, this can expose tokens and authentication credentials in server logs.
- CVE-2026-111761Medium
A2A Java SDK before 1.3.0.Final has a vulnerability in BasePushNotificationSender that sends task data to a URL without destination validation, scheme restrictions, or redirect limits. An unauthenticated attacker can register an arbitrary destination, causing the server to send requests to internal or local resources.
Original NVD description (English source)
A2A Java SDK is the official Java SDK for the Agent2Agent (A2A) Protocol. Prior to 1.3.0.Final, a malicious or compromised remote agent can cause the default JDK-based client to forward a configured API key to a third-party server. When a client application configures credentials through `CredentialService`, `AuthInterceptor.intercept` in `client/transport/spi/src/main/java/org/a2aproject/sdk/client/transport/spi/interceptors/auth/AuthInterceptor.java` uses `APIKeySecurityScheme.name()` from the remote AgentCard directly as the HTTP header name containing the credential, without checking that the declared location is HEADER. JdkA2AHttpClient uses followRedirects(NORMAL), so an agent-controlled cross-origin redirect forwards the custom credential-bearing header even when the standard Authorization header is stripped. The attack requires configured API key credentials for the agent's security scheme and control of the agent's AgentCard and redirect response, but no additional client privileges. This issue is fixed in version 1.3.0.Final.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS