CVE-2026-48579 Microsoft Exchange Online Information Disclosure Vulnerability

What is CVE-2026-48579?

CVE-2026-48579 is a critical missing authorization vulnerability in Microsoft Exchange Online, published on 4 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Improper authorization in Microsoft Exchange Online allows an unauthorized attacker to disclose information over a network.

Weakness: CWE-285

Which versions are affected by CVE-2026-48579?

It affects 1 product.

Products include Microsoft Exchange Online.

How do I fix CVE-2026-48579?

No fix has been published for CVE-2026-48579 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-2026-48579 being exploited?

There is no known exploitation of CVE-2026-48579 in the wild and no public exploit code.

Other vulnerabilities in Microsoft Exchange Online

• CVE-2026-65801 Microsoft Exchange Online Elevation of Privilege Vulnerability Critical 10.0
• CVE-2026-56191 Microsoft Exchange Online Tampering Vulnerability Critical 10.0
• CVE-2026-48582 Microsoft Exchange Online Elevation of Privilege Vulnerability Critical 9.6
• CVE-2026-54998 Microsoft Exchange Online Elevation of Privilege Vulnerability High 8.8

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-jwv5-9w8q-m2j8.