Over 29,000 Exchange servers unpatched against high-severity flaw

[rbc]

Over 29,000 Exchange servers exposed online remain unpatched against a high-severity vulnerability that can let attackers move laterally in Microsoft cloud environments, potentially leading to complete domain compromise.

The security flaw (tracked as CVE-2025-53786) helps threat actors who gain administrative access to on-premises Exchange servers to escalate privileges within the organization's connected cloud environment by forging or manipulating trusted tokens or API calls, without leaving easily detectable traces and making it hard to detect exploitation.

CVE-2025-53786 affects Exchange Server 2016, Exchange Server 2019, and Microsoft Exchange Server Subscription Edition, which replaces the perpetual license model with a subscription-based one, in hybrid configurations.
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Over 29,000 Exchange servers unpatched against high-severity flaw