CVE-2026-56191
Critical
Description
Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.
SeverityCritical
CVSS10.0
Exploit probability—
Product
Microsoft Exchange Online
PublishedJul 24, 2026
First seenJul 24, 2026
Weakness typeCWE-287Improper authentication
How to fix
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| microsoft exchange_online | No range specified | — |
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