CVE-2026-56191
Title: Microsoft Exchange Online Improper Authentication Tampering
Auth Bypass
Proof Of Concept
No public PoC currently indexed for CVE-2026-56191.
CWE Category
CWE-287
Published Date
Jul 24, 2026
Modified Date
Jul 29, 2026
Exploit Status
Not Found
Score
10.0
CVSS v3.1
Exploit Probability (EPSS)
0.76%
Vulnerability Summary
CVE-2026-56191: Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.
Impacted Vendors
Reference Links
CVSS v3.1
Source Entity
[email protected]
Severity
CRITICAL
10.0
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
CHANGED
RAW VECTOR
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Associated Attack Patterns (CAPEC)
Total: PatternsNo specific attack patterns mapped.
Likelihood
Severity
Page /
CVE-2026-56191 Exploits & PoCs (Proof Of Concept)
No public PoCs found in our database for this CVE.
MODIFIED
Vulnerability data updated via NVD.
MODIFIED
Vulnerability data updated via NVD.
MODIFIED
Vulnerability data updated via NVD.
MODIFIED
Vulnerability data updated via NVD.
MODIFIED
Vulnerability data updated via NVD.
Attack Vector Matrix
Access Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
NONE
CVSS Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Affected Stack
No specific products linked.