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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
2026-07-23
Advisory published
2026-06-04
Advisory updated
2026-07-23

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.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-48579 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-48579

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-48579 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-48579

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.