CVE-2026-56191

criticalpriority · track · 0EPSS 0.009 · 60 %ileDEEUUS
grimoire priorityP2 · Scheduled
Exploitable?
—
no known exploitation
Likely / severe?
0.90% (60th) EPSS
CVSS 10 · critical
Is it mine?
4 products
Check your exposure
Who says so?
5 sources
cnnvd · enisa_euvd · cert_bund · msrc_csaf

EPSS · scored 2026-10-27

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

01

cvss

Technical severity, 0–10. One row per scoring source.

10.0
010

base score 0–10 · higher = more severe · hover a vector to decode

v3.110criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:Csecondary · ENISA EU
v3.110criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:Hsecondary · secure@microsoft.com USexploitability 3.9 · impact 6
v3.19.1criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)
v3.110criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:Csecondary · Microsoft Security Response Center US
02

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: totalcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-287USCWE-287US
04

affected products (4)

Products and version ranges known to be affected.

05

advisories (2)

Vendor and ecosystem advisories describing this.

  • WID-SEC-W-2026-2502Microsoft Azure, Copilot, Exchange, Surface: Mehrere SchwachstellenDeutsch2026-07-23csaf · cert_bundDE

    Ein Angreifer kann mehrere Schwachstellen in Microsoft Azure, Microsoft 365 Copilot, Microsoft Exchange und Microsoft Apps Surface ausnutzen, um seine Privilegien zu erhöhen, beliebigen Code auszuführen, Daten zu manipulieren oder vertrauliche Informationen offenzulegen.

  • msrc_CVE-2026-56191Microsoft Exchange Online Tampering Vulnerability2026-07-23csaf · msrc_csafUS

    To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle

06

also known as (3)

Other names and identifiers for this entity.

07

sources

Which sources assert this record, and when.

cnnvdenisa_euvdcert_bundmsrc_csafnvdNVDCVE.orgMITRE
published 2026-07-24modified 2026-10-24
08

references (3)

External citations — patches, advisories, analysis.

scry

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