CVE-2026-55126
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 Office SharePoint allows an authorized attacker to perform spoofing over a network.
In the news
Third-party coverage- Microsoft July 2026 Patch Tuesday fixes massive 570 flaws, 3 zero-days
- 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 Office SharePoint stemming from improper neutralization of input during web page generation. This allows an authenticated attacker to inject malicious scripts into dynamically generated pages, enabling session hijacking, credential theft, or spoofing of legitimate users.
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< 16.0.19725.20434= 2016= 2019CVSS 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
- Low
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/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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Identify SharePoint Server versionRun PowerShell command: (Get-SPFarm).BuildVersion or check registry at HKLM\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\16.0\SharePoint\Setup\VersionAffected if Version is below 16.0.19725.20434, or the product version is SharePoint Server 2016 or 2019 (any build)
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Confirm SharePoint web applications are accessibleAccess SharePoint Central Administration site or any published SharePoint web application URL in a browserAffected if Web applications are reachable and the server is running SharePoint (required for XSS to be exploitable)
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Verify authentication is enabledCheck SharePoint authentication settings via Central Administration > Application Management > Manage web applications > Authentication ProvidersAffected if Anonymous or Forms-based authentication is enabled, as the XSS requires an authenticated user session to exploit
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Review custom web parts or farm solutionsInspect any custom web parts, timer jobs, or farm solutions deployed via Central Administration > System Settings > Manage farm solutionsAffected if Custom code is deployed that handles user input without proper encoding, increasing XSS attack surface
You are affected if your SharePoint Server version is below 16.0.19725.20434, or if you are running SharePoint Server 2016 or 2019, and the server is accessible with authenticated user access to web applications.
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.
dbcve · scoped16.0.19725.20434
Apply Microsoft-provided SharePoint patches when released; until then, implement output encoding and input validation on SharePoint server configurations, and restrict authenticated user permissions where possible.
16.0.19725.20434 or later for SharePoint Subscription; apply latest security updates for SharePoint Server 2016 and 2019
- Check your current SharePoint Server version using SharePoint Administration Center or Get-SPFarm cmdlet
- For SharePoint Server 2019: Apply the latest security update (CVE-2026-55126) from Microsoft Monthly Security Updates
- For SharePoint Server 2016: Apply the latest security update (CVE-2026-55126) from Microsoft Monthly Security Updates
- If using newer SharePoint Server (Subscription): Upgrade to version 16.0.19725.20434 or later
- Test the patch in a staging environment before deploying to production
- Verify the patch was applied successfully by checking the version number post-installation
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-55126 — 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-2026-55126 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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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.
- 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