Medium, CVSS 5.7MavenAmendedPublished
A2A Java SDK send client credentials under server-controlled HTTP header name, enabling leakage via redirect
CVE-2026-111763 · GHSA-9rhm-2h4x-jwmx
- Affected
- Maven org.a2aproject.sdk:a2a-java-sdk-parent < 1.3.0.Final
- Fixed in
- 1.3.0.Final· Vendor fix available
- Issue
- Impact. A malicious or compromised A2A agent can cause the client's API key credential to be forwarded to an arbitrary third-party server. The agent serves an AgentCard with an APIKeySecurityScheme specifying a custom header name, then responds with an HTTP redirect. The JDK HttpClient follows the redirect and forwards the custom header containing the credential, since only the standard Authorization header may be stripped on cross-origin redirects. Where. client/transport/spi/src/main/java/org/a2aproject/sdk/client/transport/spi/interceptors/auth/AuthInterceptor.java:69 in intercept What. The apiKeySecurityScheme.name() field from the remote agent's AgentCard (untrusted, server-controlled data) is used directly as the HTTP header name when placing client credentials. Combined with JdkA2AHttpClient's followRedirects(NORMAL) policy, credentials under custom header names survive cross-origin redirects (only Authorization is stripped on newer JDKs), allowing a malicious agent to leak…
Recommended action: Upgrade to 1.3.0.Final or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.