The flaw is tracked as CVE-2026-96940 and carries a CVSS score of 8.8. According to the advisory, weak authorization in Exchange Server allows an authenticated attacker to elevate privileges over a network. While the article excerpt does not detail the full impact, the headline indicates the flaw lets authenticated attackers read other users' mailboxes.

Because this is an out-of-band release, affected organizations should prioritize patching rather than waiting for the regular monthly update cycle.

Key points:

• Vulnerability: CVE-2026-96940
• Severity: 8.8 (CVSS)
• Product: Microsoft Exchange Server
• Type: Weak authorization leading to privilege escalation
• Fix: Out-of-band security updates from Microsoft

If you run Exchange on-premises, check Microsoft's guidance and apply the updates as soon as your change window allows. Given the mailbox access implications, reviewing authentication logs and mailbox access patterns for unusual activity is also worth considering.

Source: The Hacker News

Has your organization already applied the out-of-band Exchange updates, or are you still assessing exposure?