Axios: Denial of Service via Unhandled 'error' Event in HTTP/2 ClientHttp2Session Initialization

## Summary Axios versions with Node.js HTTP/2 support can terminate the caller’s process when a ClientHttp2Session emits an error event that is not handled by axios. This affects applications that use the Node HTTP adapter with httpVersion: 2. A malicious, unavailable, or non-HTTP/2 endpoint can cause an uncaught exception instead of a normal rejected axios request. ## Impact The impact is denial of service. In affected applications, an attacker who can influence the request destination, or operate the destination server, may be able to crash the Node.js process. This does not affect default HTTP/1.1 usage, browser XHR/fetch adapters, or applications that do not enable axios HTTP/2 support. ## Affected Functionality Affected path: - Node.js HTTP adapter - httpVersion: 2 - HTTP/2 session creation/reuse through Http2Sessions - Network/session failures emitted as ClientHttp2Session error events Caller-controlled http2Options can make the issue easier to trigger, but passing arbitrary attacker input into axios config is caller-controlled behavior and should not be the primary advisory framing. ## Technical Details Http2Sessions.getSession() creates a session with http2.connect(authority, options) but only registers a close handler. It does not register an error handler on the returned ClientHttp2Session. When the session emits error, Node treats it as an unhandled EventEmitter error and throws. This can bypass the normal axios Promise rejection path and terminate the process. ##