ADV190014 | Microsoft Live Accounts Elevation of Privilege Vulnerability

Security Advisory
Published: 08/13/2019

An elevation of privilege vulnerability exists in Outlook Web Access (OWA) regarding a possible unsigned token. An attacker who successfully exploited this vulnerability could have access to another person's email inbox.

To exploit this vulnerability, an attacker would first have to replace an unsigned token with a different one.

This vulnerability has been mitigated for all users' Microsoft Live accounts.

Security Updates

To determine the support life cycle for your software version or edition, see the Microsoft Support Lifecycle.

Product Platform Article Download Impact Severity Supersedence
Microsoft Exchange Online Elevation of Privilege Important
Microsoft Office 365 Elevation of Privilege Important Elevation of Privilege Important


Microsoft has not identified any mitigating factors for this vulnerability.


Microsoft has not identified any workarounds for this vulnerability.


Does my network administrator need to do anything to protect me from this attack?
No, Microsoft has mitigated the attack vector to protect online mailboxes from this vulnerability. No further action is required.


See acknowledgements for more information.


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Version Date Description
1.0 08/13/2019 Information published.