CVE-2026-48579
Microsoft Exchange Online has a flaw that lets an attacker read data from the server without permission. The weakness is an authorization error that can be triggered from anywhere on the internet. It could expose sensitive emails or other information.
No official fix yet. If none appears within 45 days of first tracking, this entry is removed automatically.
Who is affected
Microsoft Exchange Online services used by organizations that host email and collaboration data in Microsoft 365. Any user or admin of an Exchange Online tenant could be impacted.
Real-world impact
An attacker could read confidential emails, calendar entries, or other data stored in Exchange Online, potentially revealing personal or corporate secrets.
Why this severity
The CVSS score of 9.1 reflects that the vulnerability can be exploited over the network without any authentication, and it gives an attacker full confidentiality compromise. The lack of required privileges and the high impact on data confidentiality drive the score.
What to do about it
No official fix or mitigation is documented in the sources yet. Monitor the vendor advisory and apply the patch as soon as it is released.
No fix documented in sources
Timeline
- Jun 4, 2026 · Jun 4, 2026PublishedDisclosed and added to the National Vulnerability Database.
- Jul 23, 2026 · 12d agoAdvisory updatedThe NVD record was last revised.
How it’s attacked
References & advisories
- msrc.microsoft.com/update-guide/vulnerability/…vendor advisory