Sha256: 260f82fd213fe430f92f058ef001cd778deba87764627a70397ad4be13c846b9
Contents?: true
Size: 1.95 KB
Versions: 3
Compression:
Stored size: 1.95 KB
Contents
---
gem: rack
cve: 2018-16471
url: https://groups.google.com/forum/#!topic/ruby-security-ann/NAalCee8n6o
title: Possible XSS vulnerability in Rack
date: 2018-11-05
description: |
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
```
patched_versions:
- "~> 1.6.11"
- ">= 2.0.6"
Version data entries
3 entries across 3 versions & 2 rubygems