CVE-2026-111763
A2A Java SDK send client credentials under server-controlled HTTP header name, enabling leakage via redirect
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.
INFO
Published Date :
Oct. 20, 2026, 4:17 p.m.
Last Modified :
Oct. 20, 2026, 4:17 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update A2A Java SDK to version 1.3.0.Final.
- Verify credential forwarding configuration.
- Review agent security scheme configurations.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-111763.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-111763 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-111763
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-111763 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-111763 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Oct. 20, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-522 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/111xxx/CVE-2026-111763.json">CVE-2026-111763</a> Added Reference https://github.com/a2aproject/a2a-java/commit/2a36530d75e11bcf9b81f543464dbe193ca6478e Added Reference https://github.com/a2aproject/a2a-java/pull/1097 Added Reference https://github.com/a2aproject/a2a-java/releases/tag/v1.3.0.Final Added Reference https://github.com/a2aproject/a2a-java/security/advisories/GHSA-4fpj-g9jf-9rgg Added Reference https://github.com/a2aproject/a2a-java/security/advisories/GHSA-9rhm-2h4x-jwmx