Microsoft Exchange Online vulnerabilities

5 CVEs affecting Microsoft Exchange Online, 0 known to be exploited (CISA KEV), with EPSS scores. Latest: CVE-2026-65801, published 2026-08-20.

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Known exploited (CISA KEV) first, then by EPSS exploit probability.

• CVE-2026-48579, published 2026-06-04. High severity, CVSS 7.5. EPSS: 1% chance of exploitation in the next 30 days. Improper authorization in Microsoft Exchange Online allows an unauthorized attacker to disclose information over a network.
• CVE-2026-65801, published 2026-08-20. Critical severity, CVSS 10.0. EPSS: 0.9% chance of exploitation in the next 30 days. Server-side request forgery (ssrf) in Microsoft Exchange Online allows an unauthorized attacker to elevate privileges over a network.
• CVE-2026-56191, published 2026-07-24. Critical severity, CVSS 10.0. EPSS: 0.9% chance of exploitation in the next 30 days. Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.
• CVE-2026-54998, published 2026-07-02. High severity, CVSS 8.8. EPSS: 0.8% chance of exploitation in the next 30 days. Incorrect authorization in Microsoft Exchange Online allows an authorized attacker to elevate privileges over a network.
• CVE-2026-48582, published 2026-06-19. Critical severity, CVSS 9.6. EPSS: 0.7% chance of exploitation in the next 30 days. Missing authorization in Microsoft Exchange Online allows an authorized attacker to elevate privileges over a network.