Safely inject credentials in HTTP headers with Vercel Sandbox
Vercel just closed a critical attack surface for AI agents. Credentials now live outside the sandbox—even if prompt injection succeeds, there's nothing to steal.
Why it matters
As AI agent workflows scale, credential exfiltration is becoming a vector for compromise. Vercel's header injection feature lets developers run untrusted code safely by enforcing credential isolation at the network layer, not the code layer—a critical shift for production AI deployments.
The key facts
8 to knowFeature: HTTP header injection for outbound requests from sandboxed code
Credentials stored outside sandbox VM boundary to prevent exfiltration
Designed specifically for AI agent workflows vulnerable to prompt injection
Supports domain matching with exact and wildcard rules (e.g., *.github.com)
Injected headers overwrite sandbox-set headers (full replacement, not additive)
Can be updated on running sandbox without restart (multi-phase workflows)
Available to Pro and Enterprise Vercel customers
Works with all network policy configurations including open internet access
Go to the source
Vercel Blogvercel.com
Publisher excerpt: can now automatically inject HTTP headers into outbound requests from sandboxed code. This keeps API keys and tokens safely outside the sandbox VM boundary, so apps running inside the sandbox can call authenticated services without ever accessing the credentials. Header injection is configured as…