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CVE-2026-107858: Cross-Site WebSocket Hijacking and Permissive CORS in Google Agent Development Kit (ADK) for Java Development Server

• Severity: high (CVSS 7.2 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-23 · updated 2026-10-23
• Weakness: CWE-306

Description

Missing Origin Validation in WebSockets (CWE-1385) and Permissive Cross-domain Policy with Untrusted Domains (CWE-942) in the development web server (ADK Web) in Google Agent Development Kit (ADK) for Java (com.google.adk:google-adk-dev versions 0.1.0 before 1.13.0 and com.google.adk:google-adk-maven-plugin versions 0.3.0 before 1.13.0) allow a remote attacker to control a locally running agent and read its data via a malicious web page visited by a developer while the server is running. The /run_live WebSocket endpoint accepts connections from any origin by default (hardcoded via setAllowedOrigins("*") in versions 0.1.0 through 1.5.0, and defaulting to * via adk.web.cors.origins in versions 1.6.0 through 1.12.0), and since version 0.4.0 the REST API returns Access-Control-Allow-Origin: * by default. Because the server has no authentication and requests originate from the developer's browser (so binding to localhost does not prevent exploitation), a cross-origin page can send messages to the agent (triggering registered tools), stream agent responses, and list, read, create, or delete sessions and artifacts. In versions 1.6.0 through 1.12.0, users can mitigate the issue by setting the adk.web.cors.origins property to an explicit allowlist of trusted origins (such as http://localhost:8000). The vulnerability is fixed in version 1.13.0, which enforces a same-origin default for CORS and the /run_live WebSocket endpoint, and rejects DNS-rebinding requests over loopback.

Affected products

• Google Agent Development Kit (ADK) for Java: from 0.1.0 before 1.13.0 — fixed in 1.13.0

How to fix

Upgrade to a fixed version: Google Agent Development Kit (ADK) for Java 1.13.0. Check the vendor advisory for mitigations.

References

• https://github.com/google/adk-java/commit/1ae5078072e13e101318e32833f1db323ef084e1
• https://github.com/google/adk-java/commit/5667d382ab5078a0d6e8f7184713a6bab767e004
• https://github.com/google/adk-java/commit/c2b087cbaf44f44d20dc946d8f2391506a2fce3d
• https://github.com/google/adk-java/issues/1257
• https://github.com/google/adk-java/pull/1222
• https://github.com/google/adk-java/releases/tag/v1.13.0
• https://github.com/google/adk-java/releases/tag/v1.6.0

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