GHSA-m63j-wh5w-c252

Опубликовано: 13 мар. 2019

Источник: github

Github: Прошло ревью

CVSS3: 7.5

Описание

Denial of Service Vulnerability in Action View

Impact

Specially crafted accept headers can cause the Action View template location code to consume 100% CPU, causing the server unable to process requests. This impacts all Rails applications that render views.

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

Releases

The 6.0.0.beta3, 5.2.2.1, 5.1.6.2, 5.0.7.2, and 4.2.11.1 releases are available at the normal locations.

Workarounds

This vulnerability can be mitigated by wrapping render calls with respond_to blocks. For example, the following example is vulnerable:

class UserController < ApplicationController def index render "index" end end

But the following code is not vulnerable:

class UserController < ApplicationController def index respond_to |format| format.html { render "index" } end end end

Implicit rendering is impacted, so this code is vulnerable:

class UserController < ApplicationController def index end end

But can be changed this this:

class UserController < ApplicationController def index respond_to |format| format.html { render "index" } end end end

Alternatively to specifying the format, the following monkey patch can be applied in an initializer:

$ cat config/initializers/formats_filter.rb # frozen_string_literal: true ActionDispatch::Request.prepend(Module.new do def formats super().select do |format| format.symbol || format.ref == "*/*" end end end)

Please note that only the 5.2.x, 5.1.x, 5.0.x, and 4.2.x 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.

Also note that the patches for this vulnerability are the same as CVE-2019-5418.

Credits

Thanks to John Hawthorn john@hawthorn.email of GitHub

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