Affects Microsoft Exchange Online, a widely used enterprise cloud service; potential for broad data exposure.
CVE-2026-48579
Unauthorized data disclosure in Exchange Online due to improper authorization.
Is CVE-2026-48579 being exploited?
Not confirmed. CVE-2026-48579 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 1.0% probability of exploitation in the next 30 days.
How severe is CVE-2026-48579?
CVE-2026-48579 is rated Critical. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-48579?
Yes. A fix has been recorded for CVE-2026-48579. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-48579 affect?
CVE-2026-48579 affects Microsoft Exchange Online. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-48579?
Patch when released; enforce least privilege; monitor for exfiltration
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Info disclosure over the network due to improper authorization in Exchange Online.
Patch when possible