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CVE-2026-111763— A2A Java SDK send client credentials under server-controlled HTTP header name, enabling leakage via redirect

Quick assessment

Affected
a2aproject a2a-java
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

A2A Java SDK 是 Agent2Agent（A2A）协议的官方 Java 软件开发工具包。在 1.3.0.Final 版本之前，恶意或已被攻陷的远程代理可致使基于默认 JDK 的客户端将配置的 API 密钥转发至第三方服务器。当客户端应用程序通过 配置凭据时， 文件中的 方法会直接使用远程 AgentCard 中 的返回值作为承载凭据的 HTTP 请求头名称，而并未验证该声明的位置是否为 HEADER。由于 启用了 ，因此由代理控制的跨域重定向会将携带自定义凭据的请求头一并转发，即使标准的 请求头已被剥离

CVSS 5.7 · Medium
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I. Basic Information for CVE-2026-111763

Vulnerability Information
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Vulnerability Title
A2A Java SDK send client credentials under server-controlled HTTP header name, enabling leakage via redirect
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
不充分的凭证保护机制
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
a2aproject a2a-java < 1.3.0.Final -

II. Public POCs for CVE-2026-111763

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III. Intelligence Information for CVE-2026-111763

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Vendor Pages for CVE-2026-111763 (1)

Other References for CVE-2026-111763 (4)

Same Patch Batch · a2aproject · 2026-10-20 · 5 CVEs total

CVE-2026-111765 7.5 HIGH A2A Java SDK: Android synchronous POST forwards credentials across authorities after incom
CVE-2026-111764 7.5 HIGH A2A Java SDK has a fail-open default task authorization
CVE-2026-111761 5.8 MEDIUM A2A Java SDK has Server-Side Request Forgery (SSRF) in push-notification delivery
CVE-2026-111762 5.7 MEDIUM A2A Java SDK: Push notification credentials logged in cleartext on protobuf parse failure

IV. Related Vulnerabilities

Same product: a2a-java
Same vendor: a2aproject
Same weakness: CWE-522

V. Comments for CVE-2026-111763

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