CVE-2026-56191: Microsoft Exchange Online Tampering Vulnerability
Published Jul 23, 2026
·Updated
Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.
Other sources
Microsoft Exchange Online Tampering Vulnerability
— Microsoft
Affected Software
2 affected components
Microsoft Exchange Online
Microsoft Exchange Online
Event History
Jul 23, 2026
CVE Published
via Microsoft·02:00 PM
Data Sourced
via Microsoft·02:00 PM
DescriptionSeverityWeaknessAffected Software
Updated
via Microsoft·02:00 PM
Description
Jul 24, 2026
CVE Published
via MITRE·12:01 AM
Data Sourced
via MITRE·12:01 AM
DescriptionSeverity
Data Sourced
via NVD·01:17 AM
DescriptionSeverityWeaknessAffected Software
Frequently Asked Questions
1
What is the severity of CVE-2026-56191?
CVE-2026-56191 has a critical severity rating of 10.
2
What does CVE-2026-56191 affect?
CVE-2026-56191 affects Microsoft Exchange Online.
3
How do I fix CVE-2026-56191?
To fix CVE-2026-56191, apply the latest security patches provided by Microsoft for Exchange Online.
4
What type of vulnerability is CVE-2026-56191?
CVE-2026-56191 is a tampering vulnerability due to improper authentication.
5
What are the potential impacts of CVE-2026-56191?
CVE-2026-56191 may allow an unauthorized attacker to tamper with data over the network.