Description
A2A Java SDK is the official Java SDK for the Agent2Agent (A2A) Protocol. Starting in version 1.3.0.Final and prior to version 1.3.2.Final, the AndroidA2AHttpClient synchronous POST path overrides the disabled-redirect setting in AndroidA2AHttpClient.createConnection() with the PostBuilder default followRedirects value of true, leaving a residual of the earlier credential-redirect fix. JSONRPCTransport and RestTransport add interceptor-produced authentication headers and call synchronous post() without disabling redirects. AuthInterceptor permits X-API-Key, API-Key, X-Auth-Token, and X-Authentication headers; Android's repackaged OkHttp strips Authorization on cross-authority redirects but retains these nonstandard headers, disclosing a complete configured API key or token to another authority. The additional exposure applies when redirect or front-door behavior is compromised separately from the credential-handling component, or those components operate in different trust domains; a completely malicious initial origin already receives the credential on the first request. Autonomous clients require no human action, while user-invoked workflows can require interaction. Explicit followRedirects(false) prevents the redirected request. The demonstrated impact is credential disclosure, not subsequent credential use, integrity or availability impact, code execution, or host compromise. This issue is fixed in version 1.3.2.Final.
Published: 2026-10-20
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: Credential Disclosure
Action: Patch
AI Analysis

Impact

The vulnerability in the A2A Java SDK causes the Android synchronous POST path to override a security setting that disables redirects, leading to the accidental forwarding of authentication headers such as X-API-Key, API-Key, X-Auth-Token, and X-Authentication across authority boundaries. As a result, a third‑party domain can obtain a full API key or token that had been configured for another authority. The exposure is limited to credential disclosure; there is no evidence that these credentials can be used for further attacks, nor is there code execution, integrity or availability impact, or host compromise. This flaw is a classic example of an improper handling of sensitive information during HTTP redirection.

Affected Systems

Affected are deployments of the a2aproject a2a-java SDK, specifically version 1.3.0.Final up to, but not including, 1.3.2.Final. Users of earlier or later releases are not impacted.

Risk and Exploitability

The CVSS score of 7.5 classifies this as a high severity issue, yet the EPSS score is currently unavailable and the vulnerability is not listed in CISA KEV, indicating limited exploitation evidence. Based on the description, the attack vector is inferred to be a functional flaw in the SDK’s redirect logic that can be triggered by any client making synchronous POSTs; no special privileges or conditions beyond normal network access appear required. Consequently, the risk is significant for any application that relies on the SDK for cross‑authority communication, especially if the application operates in mixed trust environments or exposes endpoints to untrusted users.

Generated by OpenCVE AI on October 20, 2026 at 16:49 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade the a2a-java SDK to version 1.3.2.Final or later to apply the official fix.
  • If an upgrade is not immediately possible, configure synchronous POST calls to use followRedirects=false to prevent the unintended forwarding of authentication headers.
  • Review and restrict the use of non‑standard authentication headers (X-API-Key, API-Key, X-Auth-Token, X-Authentication) to only trusted authorities within the application’s trust boundary.

Generated by OpenCVE AI on October 20, 2026 at 16:49 UTC.

Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-4fpj-g9jf-9rgg A2A Java SDK: Android synchronous POST forwards credentials across authorities after incomplete redirect fix
History

Fri, 23 Oct 2026 00:45:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 20 Oct 2026 19:00:00 +0000

Type Values Removed Values Added
First Time appeared A2aproject
A2aproject a2a-java
Vendors & Products A2aproject
A2aproject a2a-java

Tue, 20 Oct 2026 15:30:00 +0000

Type Values Removed Values Added
Description A2A Java SDK is the official Java SDK for the Agent2Agent (A2A) Protocol. Starting in version 1.3.0.Final and prior to version 1.3.2.Final, the AndroidA2AHttpClient synchronous POST path overrides the disabled-redirect setting in AndroidA2AHttpClient.createConnection() with the PostBuilder default followRedirects value of true, leaving a residual of the earlier credential-redirect fix. JSONRPCTransport and RestTransport add interceptor-produced authentication headers and call synchronous post() without disabling redirects. AuthInterceptor permits X-API-Key, API-Key, X-Auth-Token, and X-Authentication headers; Android's repackaged OkHttp strips Authorization on cross-authority redirects but retains these nonstandard headers, disclosing a complete configured API key or token to another authority. The additional exposure applies when redirect or front-door behavior is compromised separately from the credential-handling component, or those components operate in different trust domains; a completely malicious initial origin already receives the credential on the first request. Autonomous clients require no human action, while user-invoked workflows can require interaction. Explicit followRedirects(false) prevents the redirected request. The demonstrated impact is credential disclosure, not subsequent credential use, integrity or availability impact, code execution, or host compromise. This issue is fixed in version 1.3.2.Final.
Title A2A Java SDK: Android synchronous POST forwards credentials across authorities after incomplete redirect fix
Weaknesses CWE-522
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}

Subscriptions

A2aproject A2a-java
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-22T21:32:18.921Z

Reserved: 2026-10-16T17:52:09.082Z

Link: CVE-2026-111765

cve-icon Vulnrichment

Updated: 2026-10-22T21:32:14.246Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-20T16:17:00.830

Modified: 2026-10-22T22:18:01.380

Link: CVE-2026-111765

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-20T18:45:13Z

Weaknesses
  • CWE-522

    Insufficiently Protected Credentials