CVE-2026-54998 Microsoft Exchange Online Elevation of Privilege Vulnerability
An authorized attacker can elevate privileges in Microsoft Exchange Online due to incorrect authorization checks.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-54998?
CVE-2026-54998 is a high-severity vulnerability in Microsoft Exchange Online, published on 2 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Incorrect authorization in Microsoft Exchange Online allows an authorized attacker to elevate privileges over a network.
Weakness: CWE-863
Which versions are affected by CVE-2026-54998?
It affects 1 product.
Products include Microsoft Exchange Online.
How do I fix CVE-2026-54998?
No fix has been published for CVE-2026-54998 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-54998 being exploited?
There is no known exploitation of CVE-2026-54998 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in Microsoft Exchange Online
Sources
Also known as GHSA-phr2-vr74-whpx.