CVE-2026-56191 Details
Description
Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.
A vulnerability exists in Microsoft Exchange Online due to improper authentication, which enables an unauthorized attacker to manipulate data over the network. This issue is classified as a tampering vulnerability and has been assigned a maximum severity rating of critical.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jul 24, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56191 | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-287 | Improper Authentication | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| microsoft exchange online | All versions |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 29, 2026 | Initial Analysis | [email protected] |
| Jul 25, 2026 | CVE Modified | CISA-ADP |
| Jul 24, 2026 | CVE Modified | CISA-ADP |
| Jul 24, 2026 | New CVE Received | [email protected] |