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Action Pack contains Information Disclosure / Unintended Method Execution vulnerability

High severity GitHub Reviewed Published May 5, 2021 to the GitHub Advisory Database • Updated Jul 5, 2023

Package

bundler actionpack (RubyGems)

Affected versions

>= 6.0.0, <= 6.0.3.6
>= 6.1.0, <= 6.1.3.1
>= 5.2.5, < 5.2.6
>= 2.0.0, <= 5.2.4.5

Patched versions

6.0.3.7
6.1.3.2
5.2.6
5.2.4.6

Description

Impact

There is a possible information disclosure / unintended method execution vulnerability in Action Pack when using the redirect_to or polymorphic_url helper with untrusted user input.

Vulnerable code will look like this.

redirect_to(params[:some_param])

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

To work around this problem, it is recommended to use an allow list for valid parameters passed from the user. For example,

private def check(param)
  case param
  when "valid"
    param
  else
    "/"
  end
end

def index
  redirect_to(check(params[:some_param]))
end

Or force the user input to be cast to a string like this,

def index
  redirect_to(params[:some_param].to_s)
end

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.

  • 5-2-information-disclosure.patch - Patch for 5.2 series
  • 6-0-information-disclosure.patch - Patch for 6.0 series
  • 6-1-information-disclosure.patch - Patch for 6.1 series

Please note that only the 5.2, 6.0, and 6.1 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

Thanks to Benoit Côté-Jodoin from Shopify for reporting this.

References

Reviewed May 5, 2021
Published to the GitHub Advisory Database May 5, 2021
Published by the National Vulnerability Database May 27, 2021
Last updated Jul 5, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS score

1.403%
(87th percentile)

CVE ID

CVE-2021-22885

GHSA ID

GHSA-hjg4-8q5f-x6fm

Source code

No known source code
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