id: GO-2022-0520
modules:
    - module: std
      versions:
        - fixed: 1.17.12
        - introduced: 1.18.0-0
          fixed: 1.18.4
      vulnerable_at: 1.18.3
      packages:
        - package: net/http
          symbols:
            - Header.Clone
summary: Exposure of client IP addresses in net/http
description: |-
    Client IP adresses may be unintentionally exposed via X-Forwarded-For headers.

    When httputil.ReverseProxy.ServeHTTP is called with a Request.Header map
    containing a nil value for the X-Forwarded-For header, ReverseProxy sets the
    client IP as the value of the X-Forwarded-For header, contrary to its
    documentation.

    In the more usual case where a Director function sets the X-Forwarded-For header
    value to nil, ReverseProxy leaves the header unmodified as expected.
published: 2022-07-28T17:23:05Z
credits:
    - Christian Mehlmauer
references:
    - fix: https://go.dev/cl/412857
    - fix: https://go.googlesource.com/go/+/b2cc0fecc2ccd80e6d5d16542cc684f97b3a9c8a
    - report: https://go.dev/issue/53423
    - web: https://groups.google.com/g/golang-announce/c/nqrv9fbR0zE
cve_metadata:
    id: CVE-2022-32148
    cwe: 'CWE-200: Information Exposure'
    description: |-
        Improper exposure of client IP addresses in net/http before Go 1.17.12 and Go
        1.18.4 can be triggered by calling httputil.ReverseProxy.ServeHTTP with a
        Request.Header map containing a nil value for the X-Forwarded-For header, which
        causes ReverseProxy to set the client IP as the value of the X-Forwarded-For
        header.