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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 29 May 2026.
Exchange ServerApplication · Microsoft

CVE-2026-42897

MEDIUM · 6.1 CVSS v3.1 Published 2026-05-14
Fix available
A fix is available. Upgrade to 15.02.2562.043 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Remotely reachable No privileges

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 · unedited
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.

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 confidence

A cross-site scripting (XSS) vulnerability in Microsoft Exchange Server allows attackers to inject malicious scripts into web pages generated by the server, enabling spoofing attacks against users who access the affected Exchange interfaces.

MitigationApply the latest Microsoft Exchange Server security updates to address the XSS vulnerability; implement input validation and output encoding on Exchange web interfaces as a defense-in-depth measure.

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
Exchange ServerApplication
Affected:= 2016= 2019
Exchange Server Subscription EditionApplication
Affected:< 15.02.2562.043

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Confirm Exchange Server is installed
    Run 'Get-ExchangeServer | Select-Object Name,Edition,ServerRole' in Exchange Management Shell, or check Windows Services for 'Microsoft Exchange' services
    Affected if No Exchange Server is found - not applicable
  2. Determine the exact Exchange build number
    Run 'Get-ExchangeServer | Format-List Name,AdminDisplayVersion' in Exchange Management Shell, or check HKLM\SOFTWARE\Microsoft\ExchangeServer\v15\SetupVersion in the registry
    Affected if Build is 2016, 2019, or Subscription Edition with version < 15.02.2562.043 (compare your version against these ranges)
  3. Check if OWA virtual directory is enabled
    In Exchange Management Shell, run 'Get-OwaVirtualDirectory -Server <YourServer> | Select-Object Name,InternalUrl,ExternalUrl,Enabled'
    Affected if OWA virtual directory exists and is enabled (vulnerability affects OWA interface)
  4. Check if ECP virtual directory is enabled
    In Exchange Management Shell, run 'Get-ECPVirtualDirectory -Server <YourServer> | Select-Object Name,InternalUrl,ExternalUrl,Enabled'
    Affected if ECP virtual directory exists and is enabled (vulnerability affects ECP interface)

You are affected if Exchange Server 2016, 2019, or Subscription Edition < build 15.02.2562.043 is installed AND OWA or ECP web interfaces are accessible.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Upgrade available Upgrade to 15.02.2562.043 or later
Fixed in 15.02.2562.043
Interim mitigation

Apply the latest Microsoft Exchange Server security updates to address the XSS vulnerability; implement input validation and output encoding on Exchange web interfaces as a defense-in-depth measure.

Recommended fix Moderate confidence

Exchange Server 2016 or 2019 to the latest Cumulative Update (CU) that includes the CVE-2026-42897 fix, or Exchange Server Subscription Edition 15.02.2562.043 or later

  1. 1. Identify your current Microsoft Exchange Server version by running 'Get-ExchangeServer | Format-List Name,Edition,AdminDisplayVersion' in Exchange Management Shell
  2. 2. Navigate to the Microsoft Security Response Center (msrc.microsoft.com) and search for CVE-2026-42897 to obtain the specific security update KB article number
  3. 3. Download and apply the corresponding security update from the Microsoft Update Catalog or via Windows Update
  4. 4. After installation, verify the update was successful by checking the Exchange Server version again
  5. 5. Test critical Exchange workflows (OWA, ECP, Outlook on the web) to ensure functionality
Caveat Standard CU upgrade precautions apply - review release notes for known issues and ensure backup before applying updates

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Exchange Server Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.

Scan for this in your stack

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dbcve dependency scanner

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-42897 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data