Microsoft Defender XDR: Detection source support in alert tuning rules
Versions captured by this deployment. Earlier versions and notices may be missing; first observed is not first published.
Rollout
- Ends
- 25 Dec 2026
Rollout dates are often only in the text. When Microsoft moves them, the change shows under "What changed".
- Microsoft's start date
- 28 Sep 2026
- Last changed by Microsoft
- 28 Sep 2026
- First seen here
- 19 Oct 2026
- Versions seen
- 1
What the notice says
Microsoft's text, with its sections, lists and tables; source markup removedWhat and why
We are introducing detection source selection for alert tuning rules in Microsoft Defender XDR. This update enables alert tuning rules to be scoped to specific detection sources, providing more granular control over how alert tuning rules are applied.
As part of this update, alert tuning rules will apply to the detection sources selected for each rule. Existing rules that are not updated will apply to all detection sources under their selected service sources, including custom detections.
Rollout schedule
- Public Preview (Worldwide): Rollout begins in mid-October 2026 and is expected to complete in early November 2026.
- General Availability (Worldwide): Rollout begins in mid-November 2026 and is expected to complete in early December 2026.
- Note: Detection source selection will become available in mid-October 2026, and configured detection source selections will take effect in early November 2026.
- Note: Detection source selection will become available in mid-November 2026, and configured detection source selections will take effect in early December 2026.
Impact on your organization
Who is affected
- Organizations that use alert tuning rules in Microsoft Defender XDR.
Platforms and services
- Microsoft Defender XDR
What will happen
- Alert tuning rules will be configurable to apply to specific detection sources and apply only to the detection sources selected for each rule.
- If not updated, existing alert tuning rules will apply to all detection sources under their selected service sources, including custom detections.
Detection source selection
Action required and recommendations
No action is required if existing rules should apply to all detection sources under their selected service sources, including custom detections. Otherwise, we recommend that you review existing alert tuning rules and update the detection source selections as needed.
Compliance considerations
No compliance considerations identified. Review as appropriate for your organization.
What changed
Between the versions this installation saw, newest firstThis installation has seen one version of this notice, first on 19 Oct 2026. Later changes will show here.
Linked documentation
Microsoft pages the notice links toThe notice links to no Microsoft Learn or Support page that this installation reads.
Not confirmed here
What this page cannot tell you- Whether your tenant is affected: this is Microsoft's notice, not a check of your settings.
- Versions before 19 Oct 2026: this installation first saw the notice after Microsoft posted it.