Vulnerability · Published Jul 2, 2026 · Assigned by microsoft
CVE-2026-54998Microsoft Exchange Online Elevation of Privilege Vulnerability
High 8.8
In plain English
A high-severity incorrect authorization in Microsoft Exchange Online from Microsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.8% (higher than 56% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.
Severity (CVSS 3.1)8.8High
Exploit odds (30 days)0.8%top 44.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack tooling1Public PoC
Official description
Incorrect authorization in Microsoft Exchange Online allows an authorized attacker to elevate privileges over a network.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Microsoft Exchange Online | - |
Weakness: CWE-863 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
References
- Microsoft Exchange Online Elevation of Privilege Vulnerability vendor-advisory, patch