CVE-2026-54998

highpriority · track · 10OT risk · elevatedEPSS 0.008 · 56 %ileexploit · PoCDEEUNLRUUS

grimoire priorityP1 · Urgent

Exploitable?

Public exploit

1 exploit · PoC

Likely / severe?

0.78% (56th) EPSS

CVSS 8.8 · high

Is it mine?

9 products

Check your exposure

Who says so?

7 sources

cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

Incorrect authorization in Microsoft Exchange Online allows an authorized attacker to elevate privileges over a network.

cvss

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

8.8

010

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

v3.18.8highAV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU

v3.18.8highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:Csecondary · ENISA EU

v3.18.8highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · secure@microsoft.com USexploitability 2.8 · impact 5.9

v3.18.3highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:Psecondary · CVSS-BT (t0sche)

v3.18.8highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · NCSC-NL NL

ssvc

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

Exploitation: none · Automatable: no · Technical Impact: totalcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-863USCWE-863USCWE-863USCWE-863US

exploits (1)

Public proof-of-concept and weaponised exploit code.

sentinel-aidefense/CVE-2026-54998-expCVE-2026-54998 RCE ExploitPoC · poc_in_github

affected products (9)

Products and version ranges known to be affected.

Microsoft Exchange Onlineall versionscert_bundDEcpe:/a:microsoft:exchange:online
Microsoft Microsoft Exchange Onlineall versionsenisa_euvdEU
Microsoft Corp Microsoft Exchange Onlineall versionsfstec_bduRU
Microsoft Microsoft Exchange Online≤ vers:unknown/*ncsc_nlNL
Microsoft Microsoft Exchange Server 2016 Cumulative Update 23≤ vers:unknown/*ncsc_nlNL
Microsoft Microsoft Exchange Server 2019 Cumulative Update 14≤ vers:unknown/*ncsc_nlNL
Microsoft Microsoft Exchange Server 2019 Cumulative Update 15≤ vers:unknown/*ncsc_nlNL
Microsoft Microsoft Exchange Server Subscription Edition RTM≤ vers:unknown/*ncsc_nlNL
microsoft exchange onlineall versionsnvdUScpe:2.3:a:microsoft:exchange_online:*:*:*:*:*:*:*:*

advisories (3)

Vendor and ecosystem advisories describing this.

NCSC-2026-0234Kwetsbaarheden verholpen in Microsoft ExchangeNL2026-07-14csaf · ncsc_nlNL
Microsoft heeft kwetsbaarheden verholpen in Exchange, zowel Online als on-premise.
WID-SEC-W-2026-2191Microsoft Exchange Online: Schwachstelle ermöglicht PrivilegieneskalationDeutsch2026-07-02csaf · cert_bundDE
Ein entfernter, authentisierter Angreifer kann eine Schwachstelle in Microsoft Exchange Online ausnutzen, um seine Privilegien zu erhöhen.
msrc_CVE-2026-54998Microsoft Exchange Online Elevation of Privilege Vulnerability2026-07-02csaf · msrc_csafUS
To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cert_bund ncsc_nl nvd msrc_csaf NVD CVE.org MITRE

published 2026-07-02modified 2026-10-25

references (3)

External citations — patches, advisories, analysis.

scry

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