ash-project ash up to 3.33.10 Bulk Changeset improper authorization

Summaryinfo

A vulnerability identified as critical has been detected in ash-project ash up to 3.33.10. Affected is the function Ash.Actions.Destroy.Bulk.base_changeset/Ash.Actions.Update.Bulk.base_changeset of the component Bulk Changeset. The manipulation leads to improper authorization. This vulnerability is traded as CVE-2026-93477. It is possible to initiate the attack remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in ash-project ash up to 3.33.10. It has been rated as critical. This issue affects the function Ash.Actions.Destroy.Bulk.base_changeset/Ash.Actions.Update.Bulk.base_changeset of the component Bulk Changeset. The manipulation with an unknown input leads to a improper authorization vulnerability. Using CWE to declare the problem leads to CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Improperly Controlled Modification of Dynamically-Determined Object Attributes vulnerability in ash-project ash allows a user to set the value of a private action argument on the bulk destroy and bulk update paths. Action arguments declared with public?: false are meant to be set only by trusted server-side code (for example via Ash.Changeset.set_private_argument/3) and must not be settable from end-user input. CVE-2026-55736 fixed the non-bulk changeset path to strip private arguments from user-supplied parameter maps, but the bulk destroy and bulk update paths were not covered. Ash.Actions.Destroy.Bulk.base_changeset/5 and Ash.Actions.Update.Bulk.base_changeset/5 match every key in the caller-supplied parameter map against all of the action's arguments with no public? check, then apply the matches to the base changeset. A caller who can submit parameters to a bulk destroy or bulk update action (for example through AshJsonApi, AshGraphql, or a controller that forwards request parameters to Ash.bulk_destroy/4 or Ash.bulk_update/4) can therefore set any private argument of that action, including one referenced by an arg(...) template in the action's changes or validations. Depending on how the application uses the argument (for example an acting_user_id driving authorization or record ownership, or audit metadata), this can lead to an integrity violation or privilege escalation. The fix requires public? in the argument matching on both bulk paths; private arguments remain settable server-side via the :private_arguments option. This issue affects ash: from 2.17.15 before 3.33.11.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-93477 since 09/19/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1548.002 according to MITRE ATT&CK.

Upgrading to version 3.33.11 eliminates this vulnerability.

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Productinfo

Type

• Project Management Software

Vendor

• ash-project

Name

• ash

Version

• 3.33.0
• 3.33.1
• 3.33.2
• 3.33.3
• 3.33.4
• 3.33.5
• 3.33.6
• 3.33.7
• 3.33.8
• 3.33.9
• 3.33.10

Website

• Product: https://github.com/ash-project/ash/

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