A2A Java SDK credentials leaked via HTTP redirect

Multiple vulnerabilities in the A2A Java SDK allow malicious or compromised agents to leak client API credentials to third-party servers through HTTP redirects by exploiting insufficient validation of custom HTTP header names and redirect handling policies.

Disclosed 20 October 2026 · Record updated 20 October 2026

Impact

Client API credentials can be forwarded to arbitrary third-party servers via HTTP redirects when interacting with malicious or compromised agents.

Our coverage

A digital key slips from one messenger's hand into another's as they pass through an unsecured doorway, the path splitting unexpectedly toward a waiting stranger.

Vulnerabilities

A2A Java SDK leaks agent API keys through HTTP redirects

Two advisories published on 20 October 2026 say a malicious agent can push a client's API key to a third-party server, and that an earlier fix missed the Android path.

20 Oct 2026

Sources

github.comhttps://github.com/advisories/GHSA-9rhm-2h4x-jwmx
github.comhttps://github.com/advisories/GHSA-4fpj-g9jf-9rgg