CVE-2026-56191
Microsoft Exchange Online Tampering vulnerability
Microsoft·Microsoft Exchange Online Tampering
MSRC advisory July 23, 2026
Alert details
- Source feed
- Microsoft MSRC
- CVE ID
- CVE-2026-56191
- Affected products
- Microsoft Exchange Online Tampering · Microsoft Microsoft Exchange Online Tampering · Microsoft
What happened
Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.
What it means for your business
Microsoft Exchange Online Tampering vulnerability (CVE-2026-56191) was added to Microsoft’s security update guidance. Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network. PremierePC tracks MSRC advisories for Upstate SC businesses — patch or open a ticket if you need help verifying exposure.
Sources
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