id: GO-2023-1703
modules:
    - module: std
      versions:
        - fixed: 1.19.8
        - introduced: 1.20.0-0
          fixed: 1.20.3
      vulnerable_at: 1.20.2
      packages:
        - package: html/template
          symbols:
            - tJS
            - tJSDelimited
          derived_symbols:
            - Template.Execute
            - Template.ExecuteTemplate
summary: Backticks not treated as string delimiters in html/template
description: |-
    Templates do not properly consider backticks (`) as Javascript string
    delimiters, and do not escape them as expected.

    Backticks are used, since ES6, for JS template literals. If a template contains
    a Go template action within a Javascript template literal, the contents of the
    action can be used to terminate the literal, injecting arbitrary Javascript code
    into the Go template.

    As ES6 template literals are rather complex, and themselves can do string
    interpolation, the decision was made to simply disallow Go template actions from
    being used inside of them (e.g. "var a = {{.}}"), since there is no obviously
    safe way to allow this behavior. This takes the same approach as
    github.com/google/safehtml.

    With fix, Template.Parse returns an Error when it encounters templates like
    this, with an ErrorCode of value 12. This ErrorCode is currently unexported, but
    will be exported in the release of Go 1.21.

    Users who rely on the previous behavior can re-enable it using the GODEBUG flag
    jstmpllitinterp=1, with the caveat that backticks will now be escaped. This
    should be used with caution.
credits:
    - Sohom Datta, Manipal Institute of Technology
references:
    - report: https://go.dev/issue/59234
    - fix: https://go.dev/cl/482079
    - web: https://groups.google.com/g/golang-announce/c/Xdv6JL9ENs8
cve_metadata:
    id: CVE-2023-24538
    cwe: 'CWE-94: Improper Control of Generation of Code (''Code Injection'')'
    references:
        - https://security.gentoo.org/glsa/202311-09