module: std
package: net/http/httputil
versions:
  - fixed: go1.15.13
  - fixed: go1.16.5
  - fixed: go1.17.0
description: |
    ReverseProxy can be made to forward certain hop-by-hop headers,
    including Connection. If the target of the ReverseProxy is
    itself a reverse proxy, this lets an attacker drop arbitrary
    headers, including those set by the ReverseProxy.Director.
published: 2022-02-17T17:33:16Z
cves:
  - CVE-2021-33197
credit: Mattias Grenfeldt (https://grenfeldt.dev) and Asta Olofsson
symbols:
  - ReverseProxy.ServeHTTP
links:
    pr: https://go.dev/cl/321929
    commit: https://go.googlesource.com/go/+/950fa11c4cb01a145bb07eeb167d90a1846061b3
    context:
      - https://groups.google.com/g/golang-announce/c/RgCMkAEQjSI
      - https://go.dev/issue/46313