CVE-2026-111763

Awaiting Analysis Awaiting Analysis - Queue

API Key Exposure in A2A Java SDK via Redirect

Publication date: 2026-10-20

Last updated on: 2026-10-21

Assigner: GitHub, Inc.

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.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-10-20

Last Modified

2026-10-21

Generated

2026-11-09

AI Q&A

2026-10-20

EPSS Evaluated

2026-11-08

NVD

CVE-2026-111763

EUVD

EUVD-2026-105127

Affected Vendors & Products

Vendor	Product	Version / Range
a2aproject	a2a-java	< 1.3.0.Final

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-522	The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.

Attack-Flow Graph

Executive Summary

This vulnerability in the A2A Java SDK allows a malicious or compromised remote agent to cause the client to forward a configured API key to a third-party server. The issue occurs because the client uses a header name from the remote agent without validation, and follows redirects automatically, which can expose credentials in custom headers even when standard headers are stripped.

Detection Guidance

To detect this vulnerability, inspect network traffic for unexpected custom headers containing credentials being forwarded during HTTP redirects. Check if your A2A Java SDK version is below 1.3.0.Final. Monitor for API key exposure in logs or network captures when using the SDK's HTTP clients.

Impact Analysis

If exploited, this vulnerability could lead to unauthorized access to sensitive data or systems by exposing API keys through redirected requests. Attackers could use leaked credentials to impersonate legitimate users or services, potentially compromising data integrity or confidentiality.

Compliance Impact

This vulnerability could lead to unauthorized data exposure, violating confidentiality requirements in GDPR and HIPAA. Organizations using the affected SDK may face compliance violations due to potential data breaches resulting from credential leakage.

Mitigation Strategies

Update the A2A Java SDK to version 1.3.0.Final or later to apply the security fix. Disable automatic HTTP redirects in all HTTP clients and implement safe header allowlist validation in AuthInterceptor.

Hi! I’m here to help you understand CVE-2026-111763. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70

EPSS Chart

Security Radar

News mentioning this vulnerability

Loading related security news...