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CVE-2025-53786 is a high-severity elevation-of-privilege vulnerability affecting Microsoft Exchange Server 2016, Exchange Server 2019, and Exchange Server Subscription Edition when deployed in hybrid configurations with Exchange Online. The issue is tied to legacy hybrid authentication design in which on-premises Exchange and Exchange Online rely on a shared service principal and OAuth trust relationship. In vulnerable configurations, an attacker who has already obtained administrative control of an on-premises Exchange server can abuse that shared trust to elevate privileges into the connected cloud tenant and assume control over Exchange Online-related identity and service access. Microsoft documented the issue in connection with security changes for hybrid deployments and addressed it through April 2025 or later Exchange hotfixes together with required hybrid configuration changes, including migration to a dedicated Exchange hybrid application and cleanup of legacy shared trust credentials.
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No valid public exploits. Mallory filtered out 1 candidate as fakes, detection scripts, or README-only repos.
All candidate exploits were filtered out by Mallory's validation.
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
221 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Microsoft Exchange Server vulnerability in hybrid deployments enabling elevated privileges/silent cloud access (per title/summary).
An elevation of privilege vulnerability in Microsoft Exchange Server Hybrid Deployment reported as exploited.
A high-severity Microsoft Exchange hybrid vulnerability enabling lateral movement from on-premises Exchange into Microsoft cloud environments after an attacker gains administrative access, potentially resulting in total domain compromise.
A post-exploitation vulnerability referenced by Microsoft as a security motivation for moving Exchange hybrid deployments away from the Exchange Online shared service principal toward a dedicated Exchange hybrid app.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.