There is a possible cross site scripting (XSS) vulnerability in ActionView’s JavaScript literal escape helpers. Views that use the j
or escape_javascript
methods may be susceptible to XSS attacks.
There is a possible XSS vulnerability in the j
and escape_javascript
methods in ActionView. These methods are used for escaping JavaScript string literals. Impacted code will look something like this:
<script>let a = `<%= j unknown_input %>`</script>
or
<script>let a = `<%= escape_javascript unknown_input %>`</script>
The 6.0.2.2 and 5.2.4.2 releases are available at the normal locations.
For those that can’t upgrade, the following monkey patch may be used:
ActionView::Helpers::JavaScriptHelper::JS_ESCAPE_MAP.merge!(
{
"`" => "\\`",
"$" => "\\$"
}
)
module ActionView::Helpers::JavaScriptHelper
alias :old_ej :escape_javascript
alias :old_j :j
def escape_javascript(javascript)
javascript = javascript.to_s
if javascript.empty?
result = ""
else
result = javascript.gsub(/(\\|<\/|\r\n|\342\200\250|\342\200\251|[\n\r"']|[`]|[$])/u, JS_ESCAPE_MAP)
end
javascript.html_safe? ? result.html_safe : result
end
alias :j :escape_javascript
end
To aid users who aren’t able to upgrade immediately we have provided patches for
the two supported release series. They are in git-am format and consist of a
single changeset.
Please note that only the 5.2 and 6.0 series are supported at present. Users
of earlier unsupported releases are advised to upgrade as soon as possible as we
cannot guarantee the continued availability of security fixes for unsupported
releases.
Thanks to Jesse Campos from Chef Secure
lists.opensuse.org/opensuse-security-announce/2020-05/msg00019.html
www.openwall.com/lists/oss-security/2020/03/19/1
github.com/rails/rails/commit/033a738817abd6e446e1b320cb7d1a5c15224e9a
github.com/rails/rails/security/advisories/GHSA-65cv-r6x7-79hv
github.com/rubysec/ruby-advisory-db/blob/master/gems/actionview/CVE-2020-5267.yml
groups.google.com/forum/#!topic/rubyonrails-security/55reWMM_Pg8
lists.debian.org/debian-lts-announce/2020/03/msg00022.html
lists.fedoraproject.org/archives/list/[email protected]/message/XJ7NUWXAEVRQCROIIBV4C6WXO6IR3KSB
nvd.nist.gov/vuln/detail/CVE-2020-5267