Microsoft 365 Alert – Service Degradation – Exchange Online – Users added as members to a Microsoft 365 group in Outlook on the web may be given “Owner” permissions by default – RESOLVED

Announcements Arpan Das

29/10/2025 08:38:00 AM

NHSmail Reference: INC46668481

Microsoft Reference: EX1181125

Issue Status: RESOLVED

Issue Description: Users added as members to a Microsoft 365 group in Outlook on the web may be given “Owner” permissions by default.

Final Update: 04/11/2025 07:21:00 AM – Microsoft have confirmed using internal testing that their code fix remediated the impact.

Scope of impact: Some users added as members to a Microsoft 365 group in Outlook on the web may be given “Owner” permissions by default instead of “Member” permissions.

Root cause: The impacted component contains a long-standing code regression that has remained dormant until now.

Next steps: Microsoft are reviewing the code of the affected component to determine methods to detect similar regressions before they cause impact in the future.