CVE-2026-45500
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedImproper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
In the news
Third-party coverage- Microsoft June 2026 Patch Tuesday fixes 6 zero-days, 200 flaws
- Microsoft CVE Summary - Bleeping Computer
Surfaced from public web coverage — external links open in a new tab.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceCross-site scripting (XSS) vulnerability in Microsoft Exchange Server where user-supplied input is not properly neutralized before being rendered in web pages, allowing attackers to inject malicious scripts that execute in the context of victim users' sessions, enabling spoofing attacks.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 2016= 2019< 15.02.2562.043CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check installed Exchange Server versionOpen Exchange Management Shell and run: Get-ExchangeServer | Format-List Name, Edition, AdminDisplayVersion. Or check the version via Control Panel > Programs > Microsoft Exchange ServerAffected if Version matches Exchange 2016, Exchange 2019, or Exchange Subscription Edition below build 15.02.2562.043
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Confirm OWA web interface is enabledIn Exchange Admin Center, navigate to Servers > Virtual Directories and verify OWA (Outlook on the web) virtual directory exists and is enabled. Alternatively, run: Get-OwaVirtualDirectory -Server <ServerName>Affected if OWA virtual directory is present and enabled - this is the primary attack surface for the XSS
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Verify ECP virtual directory statusRun Get-EcpVirtualDirectory -Server <ServerName> or check via Exchange Admin Center under Server > Virtual DirectoriesAffected if ECP virtual directory is enabled - ECP is also a web-based Exchange component vulnerable to XSS injection
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Check if Exchange is exposed to unauthenticated external accessReview IIS bindings and firewall rules to determine if OWA/ECP are accessible from the internet without authentication. Run: Get-ActiveSyncVirtualDirectory to check mobile access exposureAffected if OWA or ECP is externally accessible to unauthenticated users - the CVE states attackers are unauthenticated, so external exposure increases risk
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Inspect IIS HTTP logs for XSS injection patternsLocate IIS logs at C:\inetpub\logs\LogFiles\W3SVC1 (or appropriate log directory) and search for common XSS patterns like <script, javascript:, onerror=, onload= in URLsAffected if Logs contain URL-encoded or raw XSS payloads targeting Exchange web paths - indicates attempted or successful exploitation
Your environment is affected if you run Exchange 2016, 2019, or Subscription Edition below build 15.02.2562.043 and have OWA or ECP web interfaces enabled and accessible.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data15.02.2562.043
Apply Microsoft Exchange Server security patches when available; implement output encoding and input validation as defense-in-depth; consider web application firewall rules to detect and block XSS payloads.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-45500 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-45500 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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