CVE-2026-45503 Microsoft Exchange Server Information Disclosure Vulnerability
An authorized attacker can exploit improper authorization in Microsoft Exchange Server to disclose sensitive information over the network.
- 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-2026-45503?
CVE-2026-45503 is a high-severity missing authorization vulnerability in Microsoft Exchange Server, published on 9 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Improper authorization in Microsoft Exchange Server allows an authorized attacker to disclose information over a network.
Which versions are affected by CVE-2026-45503?
It affects 2 products.
Products include Microsoft Exchange Server, Microsoft Exchange Server Subscription Edition.
How do I fix CVE-2026-45503?
No fix has been published for CVE-2026-45503 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-45503 being exploited?
There is no known exploitation of CVE-2026-45503 in the wild and no public exploit code.
Other vulnerabilities in Microsoft Exchange Server
- CVE-2024-21410 Microsoft Exchange Server Privilege Escalation
- CVE-2021-34473 Microsoft Exchange Server Remote Code Execution
- CVE-2021-26855 Microsoft Exchange Server Remote Code Execution
- CVE-2021-34523 Microsoft Exchange Server Privilege Escalation
- CVE-2023-21529 Microsoft Exchange Server Deserialization of Untrusted Data
Sources
Also known as GHSA-p44w-fhq3-v2jv.