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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-111763
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-20 16:17:00 UTC
Updated2026-10-20 19:48:50 UTC
DescriptionA2A 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.

Risk And Classification

Primary CVSS: v4.0 5.7 MEDIUM from [email protected]

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/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

Problem Types: CWE-522 | CWE-522 CWE-522: Insufficiently Protected Credentials

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary5.7MEDIUMCVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/C...
4.0CNADECLARED5.7MEDIUMCVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
Low
User Interaction
None
Confidentiality
High
Integrity
None
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA A2aproject A2a-java affected < 1.3.0.Final Not specified

References

ReferenceSourceLinkTags
github.com/a2aproject/a2a-java/commit/2a36530d75e11bcf9b81f543464dbe193c... [email protected] github.com
github.com/a2aproject/a2a-java/releases/tag/v1.3.0.Final [email protected] github.com
github.com/a2aproject/a2a-java/security/advisories/GHSA-9rhm-2h4x-jwmx [email protected] github.com
github.com/a2aproject/a2a-java/security/advisories/GHSA-4fpj-g9jf-9rgg [email protected] github.com
github.com/a2aproject/a2a-java/pull/1097 [email protected] github.com
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