Action Pack is a framework for handling and responding to web requests. Prior to 8.1.4.1 and 8.0.5.2, ActionController::Parameters#each_key delegates to the internal ActiveSupport::HashWithIndifferentAccess that holds the request parameters, so when called with a block it returns that hash instead of the Parameters instance. The hash does not respond to permitted?, so Active Model mass assignment (new, assign_attributes, update) accepts it without raising ActiveModel::ForbiddenAttributesError. An application that passes the return value of each_key to mass assignment could allow a remote, unauthenticated attacker to set attributes that the application does not permit, such as an authorization flag. This is an incomplete fix of CVE-2020-8164, which made each, each_pair and each_value return the Parameters instance but left each_key delegated. An application is affected if it passes the return value of ActionController::Parameters#each_key, called with a block, to mass assignment. Rails itself makes no such call. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.

Affected: RubyGems: actionpack

### Impact `ActionController::Parameters#each_key` delegates to the internal `ActiveSupport::HashWithIndifferentAccess` that holds the request parameters, so when called with a block it returns that hash instead of the `Parameters` instance. The hash does not respond to `permitted?`, so Active Model mass assignment (`new`, `assign_attributes`, `update`) accepts it without raising `ActiveModel::ForbiddenAttributesError`. An application that passes the return value of `each_key` to mass assignment could allow a remote, unauthenticated attacker to set attributes that the application does not permit, such as an authorization flag.

This is an incomplete fix of [CVE-2020-8164](https://github.com/advisories/GHSA-8727-m6gj-mc37), which made `each`, `each_pair` and `each_value` return the `Parameters` instance but left `each_key` delegated.

### Details The fixed releases define `Parameters#each_key` to yield each key and return the `Parameters` instance when given a block, as `each`, `each_pair` and `each_value` do, and to return an `Enumerator` without one. Code that used the return value of `each_key` as a hash now receives the `Parameters` instance, which mass assignment rejects unless it is permitted.

### Affected applications An application is affected if it passes the return value of `ActionController::Parameters#each_key`, called with a block, to mass assignment. Rails itself makes no such call.

### Workarounds Do not use the return value of `each_key`. Call it for its blo…

Affected: Ubuntu:Pro:16.04:LTS: rails, Ubuntu:Pro:18.04:LTS: rails, Ubuntu:Pro:20.04:LTS: rails, Ubuntu:Pro:22.04:LTS: rails, Ubuntu:24.04:LTS: rails, Ubuntu:26.10: rails, Ubuntu:26.04:LTS: rails

Action Pack is a framework for handling and responding to web requests. Prior to 8.1.4.1 and 8.0.5.2, ActionController::Parameters#each_key delegates to the internal ActiveSupport::HashWithIndifferentAccess that holds the request parameters, so when called with a block it returns that hash instead of the Parameters instance. The hash does not respond to permitted?, so Active Model mass assignment (new, assign_attributes, update) accepts it without raising ActiveModel::ForbiddenAttributesError. An application that passes the return value of each_key to mass assignment could allow a remote, unauthenticated attacker to set attributes that the application does not permit, such as an authorization flag. This is an incomplete fix of CVE-2020-8164, which made each, each_pair and each_value return the Parameters instance but left each_key delegated. An application is affected if it passes the return value of ActionController::Parameters#each_key, called with a block, to mass assignment. Rails itself makes no such call. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.

Ein Angreifer kann mehrere Schwachstellen in Ruby on Rails ausnutzen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Daten zu manipulieren, um falsche Informationen darzustellen, um einen Cross-Site Scripting Angriff durchzuführen und um Sicherheitsvorkehrungen zu umgehen.