module: std
package: net/http/fcgi
versions:
- fixed: go1.14.8
- fixed: go1.15.1
description: |
  When a Handler does not explicitly set the Content-Type header, the the
  package would default to “text/html”, which could cause a Cross-Site Scripting
  vulnerability if an attacker can control any part of the contents of a
  response.

  The Content-Type header is now set based on the contents of the first Write
  using http.DetectContentType, which is consistent with the behavior of the
  net/http package.

  Although this protects some applications that validate the contents of
  uploaded files, not setting the Content-Type header explicitly on any
  attacker-controlled file is unsafe and should be avoided.
cves:
- CVE-2020-24553
credit: RedTeam Pentesting GmbH
symbols:
- response.Write
- response.WriteHeader
- response.writeCGIHeader
links:
  pr: https://go.dev/cl/252179
  commit: https://go.googlesource.com/go/+/4f5cd0c0331943c7ec72df3b827d972584f77833
  context:
  - https://groups.google.com/g/golang-announce/c/8wqlSbkLdPs
  - https://go.dev/issue/40928