CVE-2026-56191

critical

Description

Improper authentication in Microsoft Exchange Online allows an unauthorized attacker to perform tampering over a network.

References

https://github.com/nando0x0a/Vuln-Skill

https://github.com/nando0x0a/ThreatForge

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56191

Details

Source: Mitre, NVD

Published: 2026-07-24

Updated: 2026-07-29

Risk Information

CVSS v2

Base Score: 10

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

Severity: Critical

CVSS v3

Base Score: 10

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Severity: Critical

EPSS

EPSS: 0.00681