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CVE-2026-48579 Microsoft CVE debrief

CVE-2026-48579 is a critical vulnerability in Microsoft Exchange Online that allows an unauthorized attacker to disclose information over a network. The vulnerability has a CVSS score of 9.1 and is classified as CRITICAL. It was published on 2026-06-04T23:17:32.830Z and modified on 2026-06-05T16:51:00.523Z.

Vendor
Microsoft
Product
Exchange Online
CVSS
CRITICAL 9.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-04
Original CVE updated
2026-06-05
Advisory published
2026-06-04
Advisory updated
2026-06-05

Who should care

Administrators and users of Microsoft Exchange Online should be aware of this vulnerability and take necessary actions to mitigate it.

Technical summary

The vulnerability is caused by improper authorization in Microsoft Exchange Online, which allows an unauthorized attacker to disclose information over a network. The CVSS vector is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Defensive priority

High

Recommended defensive actions

  • Apply the patch or mitigation provided by Microsoft.
  • Refer to the vendor advisory for more information: [ref-4](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-48579)

Evidence notes

The vulnerability is analyzed and has a CWE-285 weakness.

Official resources

CVE-2026-48579 was published on 2026-06-04T23:17:32.830Z and modified on 2026-06-05T16:51:00.523Z.