NVD / CVE Program· CNA microsoft

CVE-2025-53786: Microsoft Exchange Server Hybrid Deployment Elevation of Privilege Vulnerability

Noroxi assessment

Priority: Monitor (action score 34/100)

Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
Probability of exploitation in the next 30 days: 7.5% (FIRST EPSS); higher than 94.5% of all records.
Anyone who can reach it over the internet can trigger it. Administrator privileges are required. No user action is required. Special conditions such as timing or configuration are required.
Fixed version: Microsoft Exchange Server 2016 Cumulative Update 23 15.01.2507.055; Microsoft Exchange Server 2019 Cumulative Update 14 15.02.1544.025; Microsoft Exchange Server 2019 Cumulative Update 15 15.02.1748.024.

Low priority for now. Upgrade to Microsoft Exchange Server 2016 Cumulative Update 23 15.01.2507.055; Microsoft Exchange Server 2019 Cumulative Update 14 15.02.1544.025; Microsoft Exchange Server 2019 Cumulative Update 15 15.02.1748.024 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 8.0 · v3.1—Proof of concept Fix available

Auth bypass

BDU:2025-09477

Published: Aug 6, 2025
Updated: Jun 17, 2026
EPSS: 7.5% · 94th percentile
CWE: CWE-287

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 32 / 40 · 8.0 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 2 / 30 · 7.5%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · microsoft: 8.0; NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
Proof of concept exists, no weaponized module
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
microsoft	exchange server	cpe:2.3:a:microsoft:exchange_server
microsoft	exchange server subscription edition	cpe:2.3:a:microsoft:exchange_server_subscription_edition

Using exchange server? Add it to your stack and be the first to know about CVEs like this one. (Email server)

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

microsoft exchange server2016
microsoft exchange server2019
microsoft exchange server subscription editionbefore 15.02.2562.017

Versions reported by the vendor

Affected version ranges reported by the assigning authority (microsoft). Independent of NVD's CPE analysis and usually ahead of it.

Microsoft Microsoft Exchange Server 2016 Cumulative Update 23
- 15.01.0.0 and later · before 15.01.2507.055affected
Microsoft Microsoft Exchange Server 2019 Cumulative Update 14
- 15.02.0.0 and later · before 15.02.1544.025affected
Microsoft Microsoft Exchange Server 2019 Cumulative Update 15
- 15.02.0.0 and later · before 15.02.1748.024affected
Microsoft Microsoft Exchange Server Subscription Edition RTM
- 15.02.0.0 and later · before 15.02.2562.017affected

Same product

microsoft: all records

Other highest-scoring records for the same primary product.

CVE-2021-34523Microsoft Exchange Server Elevation of Privilege VulnerabilityKEV
96Now
CVE-2021-34473Microsoft Exchange Server Remote Code Execution VulnerabilityKEV
96Now
CVE-2021-26855Microsoft Exchange Server Remote Code Execution VulnerabilityKEV
96Now

Published before and after this one in the same product

← EarlierCVE-2024-26198Mar 12, 2024 · Microsoft Exchange Server Remote Code Execution Vulnerability
37Monitor
← EarlierCVE-2024-49040Nov 12, 2024 · Microsoft Exchange Server Spoofing Vulnerability
33Monitor
Later →CVE-2025-25005Aug 12, 2025 · Microsoft Exchange Server Tampering Vulnerability
26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
Microsoft Exchange Server 2016 Cumulative Update 23	15.01.2507.055 · KB5050674	Microsoft (MSRC)
Microsoft Exchange Server 2019 Cumulative Update 14	15.02.1544.025 · KB5050673	Microsoft (MSRC)
Microsoft Exchange Server 2019 Cumulative Update 15	15.02.1748.024 · KB5050672	Microsoft (MSRC)
Microsoft Exchange Server Subscription Edition RTM	15.02.2562.017 · KB5047155	Microsoft (MSRC)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
Source	Kind	Date
Proof-of-concept repository on GitHub	stars:0	2025-08-21

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

PublishedAug 6, 2025
First PoCAug 21, 2025+14 d
TodayNov 3, 2026+454 d

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2024-21410540 days apartMicrosoft Exchange Server Elevation of Privilege VulnerabilityKEV
73This week

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
Administrator privileges are required.
No user action is required.
Special conditions such as timing or configuration are required.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector: Network
Attack complexity: High
Privileges required: High
User interaction: None
Scope: Changed
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-287 · Improper Authentication

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

nvd-secondary

Root cause

Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.

The bug in code

The whole CWE-287 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1app.use("/admin", requireSession, adminRouter);
2

3// Route added later skips the middleware
4app.post("/admin-api/config", updateConfig);

Fixed

1const admin = express.Router();
2admin.use(requireSession, requireRole("admin"));
3

4admin.post("/config", updateConfig);
5app.use("/admin", admin);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Change log

Fix✗ → ✓Oct 18, 2026, 3:32 AM UTC

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References

msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53786

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records