🚨 [security] Update rack: 2.0.4 → 2.0.6 (patch)

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🚨 Your version of rack has known security vulnerabilities 🚨

Advisory: CVE-2018-16471
Disclosed: November 05, 2018
URL: https://groups.google.com/forum/#!topic/ruby-security-ann/NAalCee8n6o

Possible XSS vulnerability in Rack

There is a possible vulnerability in Rack. This vulnerability has been
assigned the CVE identifier CVE-2018-16471.

Versions Affected: All.
Not affected: None.
Fixed Versions: 2.0.6, 1.6.11

Impact

There is a possible XSS vulnerability in Rack. Carefully crafted requests can
impact the data returned by the scheme method on Rack::Request.
Applications that expect the scheme to be limited to "http" or "https" and do
not escape the return value could be vulnerable to an XSS attack.

Vulnerable code looks something like this:

<%= request.scheme.html_safe %>

Note that applications using the normal escaping mechanisms provided by Rails
may not impacted, but applications that bypass the escaping mechanisms, or do
not use them may be vulnerable.

All users running an affected release should either upgrade or use one of the
workarounds immediately.

Releases

The 2.0.6 and 1.6.11 releases are available at the normal locations.

Workarounds

The following monkey patch can be applied to work around this issue:

require "rack"
require "rack/request"
class Rack::Request

SCHEME_WHITELIST = %w(https http).freeze
def scheme

if get_header(Rack::HTTPS) == 'on'

'https'

elsif get_header(HTTP_X_FORWARDED_SSL) == 'on'

'https'

elsif forwarded_scheme

forwarded_scheme

else

get_header(Rack::RACK_URL_SCHEME)

end

end
def forwarded_scheme

scheme_headers = [

get_header(HTTP_X_FORWARDED_SCHEME),

get_header(HTTP_X_FORWARDED_PROTO).to_s.split(',')[0]

]
scheme_headers.each do |header|

return header if SCHEME_WHITELIST.include?(header)

end
nil

end

end

🚨 We recommend to merge and deploy this update as soon as possible! 🚨

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Here is everything you need to know about this update. Please take a good look at what changed and the test results before merging this pull request.

What changed?

↗️ rack (indirect, 2.0.4 → 2.0.6) · Repo · Changelog

Commits

See the full diff on Github. The new version differs by 10 commits:

• Bumping version for release
• Whitelist http/https schemes
• Reduce buffer size to avoid pathological parsing
• Merge tag '2.0.5' into 2-0-stable
• Merge pull request #1296 from tomelm/fix-prefers-plaintext
• Bump version for release
• Merge pull request #1268 from eileencodes/forwardport-pr-1249-to-2-0-stable
• Merge pull request #1249 from mclark/handle-invalid-method-parameters
• Stick with a passing version of Rubygems and bundler
• Leahize

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