CVE-2026-45504Public exploitNetwork attack vector

Authenticated file read via unchecked WOPI URL

Published Jun 9, 2026 · Updated Jun 9, 2026

SSRF in Microsoft Exchange Server 2016 CU23, 2019 CU14 and CU15, and SE RTM allows remote authenticated users to read local files. EWS ReferenceAttachment handling trusts a user-controlled ProviderEndpointUrl, then accepts an unvalidated file-scheme WebApplicationUrl from the attacker's WOPI response and returns the target file through the preview path. A valid low-privilege mailbox session is required; the demonstrated impact is arbitrary server-local file disclosure, not code execution.

CVSS severity8.8
High
EPSS probability0.85%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in Microsoft Exchange Server 2016 CU23, 2019 CU14 and CU15, and SE RTM allows remote authenticated users to read local files. EWS ReferenceAttachment handling trusts a user-controlled ProviderEndpointUrl, then accepts an unvalidated file-scheme WebApplicationUrl from the attacker's WOPI response and returns the target file through the preview path. A valid low-privilege mailbox session is required; the demonstrated impact is arbitrary server-local file disclosure, not code execution.

The record

CVE
CVE-2026-45504
Published
Jun 9, 2026
Updated
Jun 9, 2026
Vendor
Microsoft
Product
Microsoft Exchange Server 2019 Cumulative Update 14
Classifications
CWE-918, T1005
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=15.02.0.0 <15.02.1544.041

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft · Microsoft Exchange Server 2019 Cumulative Update 14version=15.02.0.0 <15.02.1544.041
Microsoft · Microsoft Exchange Server Subscription Edition RTMversion=15.02.0.0 <15.02.2562.043
Microsoft · Microsoft Exchange Server 2016 Cumulative Update 23version=15.01.0.0 <15.01.2507.069
Microsoft · Microsoft Exchange Server 2019 Cumulative Update 15version=15.02.0.0 <15.02.1748.046

Published CVSS scores

8.8MicrosoftCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1005Data from Local System

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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