EEF-CVE-2026-47070

HTTP/3 redirect handler leaks Authorization and Cookie headers to cross-origin redirect target in hackney

## Summary Sensitive Data Exposure vulnerability in benoitc hackney allows Retrieve Embedded Sensitive Data. The HTTP/3 redirect handler in src/hackney\_h3.erl passes the original request headers unchanged to the redirect target without performing any cross-origin check. When a client issues an HTTP/3 request with follow\_redirect enabled and includes Authorization or Cookie headers, a server responding with a 3xx redirect to a different host will cause the client to forward those credentials verbatim to the new origin. The main hackney.erl module has maybe\_strip\_auth\_on\_redirect/2 (guarded by the location\_trusted option) to address CVE-2018-1000007, but hackney\_h3.erl is missing this protection entirely. This issue affects hackney: from 3.1.1 before 4.0.1.