Action Pack: Possible Strong Parameters bypass in Parameters#each_key

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-126081
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-10 21:19:26 UTC
Updated2026-11-10 21:19:26 UTC
DescriptionAction 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Problem Types: CWE-915 | CWE-915 CWE-915: Improperly Controlled Modification of Dynamically-Determined Object Attributes

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Rails Rails affected >= 8.1, < 8.1.4.1 Not specified
CNA Rails Rails affected < 8.0.5.2 Not specified

References

ReferenceSourceLinkTags
github.com/rails/rails/security/advisories/GHSA-wm3x-v3qw-4jh3 [email protected] github.com
github.com/rails/rails/releases/tag/v8.1.4.1 [email protected] github.com
github.com/rails/rails/commit/8ba746e0a786458c281060823f2ccc5c5f6312ac [email protected] github.com
github.com/rails/rails/releases/tag/v8.0.5.2 [email protected] github.com
github.com/rails/rails/commit/2fc8838300133931e19eed3ea6cee76a7e83f19c [email protected] github.com
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