RubySec

Providing security resources for the Ruby community

CVE-2016-0751 (actionpack): Possible Object Leak and Denial of Service attack in Action Pack

ADVISORIES

GEM

actionpack

FRAMEWORK

rails

SEVERITY

CVSS v3: 7.5

CVSS v2: 5.0

PATCHED VERSIONS

  • >= 5.0.0.beta1.1
  • ~> 4.2.5, >= 4.2.5.1
  • ~> 4.1.14, >= 4.1.14.1
  • ~> 3.2.22.1

DESCRIPTION

There is a possible object leak which can lead to a denial of service vulnerability in Action Pack. This vulnerability has been assigned the CVE identifier CVE-2016-0751.

Versions Affected: All. Not affected: None. Fixed Versions: 5.0.0.beta1.1, 4.2.5.1, 4.1.14.1, 3.2.22.1

Impact

A carefully crafted accept header can cause a global cache of mime types to grow indefinitely which can lead to a possible denial of service attack in Action Pack.

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

Releases

The FIXED releases are available at the normal locations.

Workarounds

This attack can be mitigated by a proxy that only allows known mime types in the Accept header.

Placing the following code in an initializer will also mitigate the issue:

require 'action_dispatch/http/mime_type'

Mime.const_set :LOOKUP, Hash.new { |h,k|
  Mime::Type.new(k) unless k.blank?
}

Patches

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.

  • 5-0-mime_types_leak.patch - Patch for 5.0 series
  • 4-2-mime_types_leak.patch - Patch for 4.2 series
  • 4-1-mime_types_leak.patch - Patch for 4.1 series
  • 3-2-mime_types_leak.patch - Patch for 3.2 series

Please note that only the 4.1.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.

Credits

Aaron Patterson <3<3