CVE-2026-111763
Severity not reportedA2A Java SDK is the official Java SDK for the Agent2Agent (A2A) Protocol.
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.
Affected products
Not reported by the source (unknown — not "none").
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
No vendor advisory or patch reference tagged by NVD. Check the references below.
References
- https://github.com/a2aproject/a2a-java/commit/2a36530d75e11bcf9b81f543464dbe193ca6478e security-advisories@github.com
- https://github.com/a2aproject/a2a-java/pull/1097 security-advisories@github.com
- https://github.com/a2aproject/a2a-java/releases/tag/v1.3.0.Final security-advisories@github.com
- https://github.com/a2aproject/a2a-java/security/advisories/GHSA-4fpj-g9jf-9rgg security-advisories@github.com
- https://github.com/a2aproject/a2a-java/security/advisories/GHSA-9rhm-2h4x-jwmx security-advisories@github.com