Elevation of Privileges in Microsoft Exchange Online by Microsoft
CVE-2026-54998

8.8HIGH

Key Information:

Vendor

Microsoft
Status
Microsoft Exchange Online
Vendor
CVE Published:
2 July 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-54998?

A security flaw in Microsoft Exchange Online permits an attacker with valid credentials to escalate their privileges, potentially leading to unauthorized access and manipulation of sensitive data across the network. This vulnerability underscores the importance of robust access controls and monitoring for any suspicious activity in Exchange environments.

Affected Version(s)

Microsoft Exchange Online -

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-54998-exp
Created by sentinel-aidefense

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE...
vendor-advisorypatch

CVSS V3.1

Score:
8.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

.