Security Digest · Vulnerability record
CVE-2025-53786: Microsoft Exchange Server Hybrid Deployment Elevation of Privilege Vulnerability
On April 18th 2025, Microsoft announced Exchange Server Security Changes for Hybrid Deployments and accompanying non-security Hot Fix.
CVSS 8.0 High EPSS 7.7% · p95 Check exposure
Should you act?
Normal patch cycle
No exploitation signal; fix it in your next routine update if you are affected. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 7.7%, percentile 95: FIRST’s model estimates a 7.7% chance of exploitation activity in the next 30 days, higher than 95% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
- Needs an account (high (admin)). Exposure depends on who can log in.
- Editorial verdict: Check exposure. Exchange Hybrid CVE-2025-53786: On-Prem to Cloud Escalation — Not known to be exploited and requires on-prem Exchange admin first, but it turns any on-prem compromise into a quiet cloud takeover, so verify the dedicated hybrid app is in place and the old shared credential is gone.
What it is
On April 18th 2025, Microsoft announced Exchange Server Security Changes for Hybrid Deployments and accompanying non-security Hot Fix. Microsoft made these changes in the general interest of improving the security of hybrid Exchange deployments. Following further investigation, Microsoft identified specific security implications tied to the guidance and configuration steps outlined in the April announcement. Microsoft is issuing CVE-2025-53786 to document a vulnerability that is addressed by taking the steps documented with the April 18th announcement. Microsoft strongly recommends reading the information, installing the April 2025 (or later) Hot Fix and implementing the changes in your Exchange Server and hybrid environment.
Weakness type: CWE-287.
Product: Microsoft Microsoft Exchange Server 2016 Cumulative Update 23 · Assigned by: microsoft · Published: 2025-08-06
Affected and fixed versions
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 23 | 15.01.0.0 < 15.01.2507.055 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 14 | 15.02.0.0 < 15.02.1544.025 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 15 | 15.02.0.0 < 15.02.1748.024 |
| Microsoft | Microsoft Exchange Server Subscription Edition RTM | 15.02.0.0 < 15.02.2562.017 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| microsoft | 3.1 | 8 High | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C |
- Attack vector: network (remotely reachable)
- Attack complexity: high (needs special conditions)
- Privileges required: high (admin)
- User interaction: none
- Scope: changed (can affect other components)
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none, automatable no, technical impact total.
- FIRST EPSS (model of 2026-10-21): 7.71% probability of exploitation activity in the next 30 days; percentile 95.
Timeline
- — CVE record published by microsoft
- — erroneo.us brief: Exchange Hybrid CVE-2025-53786: On-Prem to Cloud Escalation
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
Vulnerability records
- CVE.org record CVE-2025-53786 cve.org
- NVD entry CVE-2025-53786 nvd.nist.gov