ACL debugging tools

Release version: Australia

Updated March 12, 2026

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Summary of ACL Debugging Tools

ACL debugging tools are designed to assist ServiceNow customers in troubleshooting and debugging Access Control Lists (ACLs). They provide detailed output messages and a configuration watcher to help understand ACL behaviors when modifications occur.

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Key Features

Field Level Debugging: Enables visibility of ACL rules associated with each field through a bug icon, allowing users to evaluate which rules apply and their results.
User Impersonation: Facilitates testing ACLs by impersonating another user to see what ACLs they pass or fail while ensuring access is limited to what the impersonated user can see.
ACL Rule Output Messages: Displays processing time, path, context, return code, and a summary of evaluations for each ACL rule in forms and lists.
Icons for Evaluation Results: Utilizes icons to indicate whether access was granted or denied, along with the origin of the evaluation (e.g., cached results).
Property Settings: Allows customization of read access to certain ACL-related tables during impersonation, which can be adjusted through system properties.

Key Outcomes

By utilizing ACL debugging tools, customers can effectively trace and understand ACL evaluations, leading to improved security configurations and faster resolutions to access issues. The real-time feedback during debugging enhances the ability to ensure that users have the correct access levels while maintaining security integrity.

Field level debugging and access ACL rule output messages are available to help you troubleshoot and debug ACLs. The ACL configuration watcher lets you know what related ACLs exist when you modify one.

Field level debugging

When debugging is enabled, a small bug icon (‎) appears beside each field with an ACL rule. Clicking the icon lists the ACL rules that apply for the field and the evaluation results. Enable debugging by navigating to System Security > Debugging > Debug Security Rules.

Figure 1. Field level security on an incident

After enabling ACL debugging, you can impersonate another user to see what ACL rules the user passes and fails. When you impersonate a user, you can only see what that user is allowed to see. For example, you cannot view a record that an ACL prevents the user from seeing. To make debugging easier, read-only access to certain ACL-related tables is enabled by default, even when impersonating a user that does not have read access to the tables. To change this functionality, set the following property to false.

To enable ACL rule debugging, navigate to System Security > Debug Security Rules.


System property	Description	Default setting
glide.security.access_acl_as_impersonator	Allows read access to the following tables while impersonating a user: sys_security_acl, sys_security_operation, sys_security_type, and sys_user_role. As a result, the impersonating user can read data that the impersonated user cannot read.	true Note: When the property is set to false, the impersonated user might be prevented from reading ACL-related data. In this case, a second session logged in as admin or security_admin might be required to debug ACLs.

ACL rule output messages

ACL debugging displays ACL rule output messages at the bottom of each list and form. The output message displays the following:


Message element	Description
TIME	The total time used to process this ACL rule.
PATH	Information that uniquely identifies each ACL rule in the format: <ACL rule type>/<ACL rule name>/<Operation>.
CONTEXT	The object being evaluated by the ACL rule.
RC	The return code of the ACL rule. A true value passes the ACL rule. A false value fails the ACL rule.
RULE	A brief summary of processors and scripts, followed by ACL results for each table-level and field-level ACL evaluation. Most ACL evaluations show an overall pass or fail result followed by a breakdown of the results for each type of ACL criteria: iAccessHandler: An internal system check using hidden source code on the platform. This is a system security check that you cannot modify. IAccessHandler can grant or deny access to a resource without evaluating ACLs. If IAccessHandler is ignored, then the ACLs are evaluated. You cannot modify the IAccessHandler checks in any way. For example, an IAccessHandler implementation is used for access checks on application resources and this cannot be changed. This is available starting with the Istanbul release. Roles: Verification that the user has the correct role. Condition: Verification that the user passed the condition specified on the ACL rule (if any). Script: Verification that the user passed the script specified on the ACL rule (if any).

The icons that appear show how the ACL was evaluated:


Icon	Description
A green checkmark (‎)	Indicates the table or field passed the criteria.
A red x icon ()	Indicates the table or field did not pass.
An empty gray circle icon (‎)	Indicates the ACL evaluation did not need to be performed.
A blue checkmark, x, or empty circle	Indicates that the ACL was taken from a cached result of a previous ACL check. The icons mean the same as the above.

You can perform these actions on the ACL debug output:

Select or clear these check boxes at the top of the debug output:
- Security rules: Show or hide the results of the ACL checks.
- Others: Show or hide other warnings or messages.
Click the name of the ACL next to any of the output messages to open that ACL record.
Hover the cursor over any of the icons for the four ACL checks to see more information.