CVE-2026-56191
Microsoft Exchange Online Tampering vulnerability
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. If you need help checking exposure, call (864) 335-9223.
Sources
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