CVE-2026-20945
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.
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 where improper input validation allows an authenticated attacker to inject malicious scripts into web pages, potentially enabling session hijacking, credential theft, or content spoofing.
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< 16.0.19725.20210= 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.
-
Check SharePoint version via PowerShellOpen SharePoint Management Shell and run: Get-SPFarm | Select-Object BuildVersionAffected if The BuildVersion returned is less than 16.0.19725.20210, or equals 16.0.x.x (SharePoint 2016), or equals 16.0.x.x (SharePoint 2019)
-
Check SharePoint version via registryNavigate to registry key HKLM\SOFTWARE\Microsoft\Office Server\16.0\Setup and inspect the 'BuildVersion' valueAffected if The BuildVersion value is lower than 16.0.19725.20210, or matches SharePoint 2016 or 2019 version numbers
-
Verify exact product via Central AdministrationAccess SharePoint Central Administration > System Settings > Manage farm servers; the Products and Versions column shows the specific SharePoint editionAffected if The product listed is SharePoint Server 2016 or SharePoint Server 2019 regardless of build number
-
Confirm authentication requirement contextReview that this XSS flaw requires an authenticated user session - meaning anonymous-only sites are not affected by this specific CVEAffected if The SharePoint environment allows authenticated user access (standard intranet/portal scenarios)
-
Identify affected web applicationsList all web applications via Get-SPWebApplication in PowerShell; the XSS vulnerability applies to any application processing user-supplied contentAffected if Any web application exists and accepts user content input
You are affected if your SharePoint Server installation is version 2016, 2019, or any build earlier than 16.0.19725.20210 and your sites allow authenticated user access.
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 · scoped16.0.19725.20210
Apply Microsoft security patches for SharePoint when available; implement output encoding and input validation for user-supplied content; configure Content Security Policy (CSP) headers to mitigate XSS execution.
SharePoint Server 2016/2019 to version 16.0.19725.20210 or later; SharePoint Server Subscription Edition to version 16.0.19725.20210 or later
- Identify the current SharePoint Server version installed in your environment (2016, 2019, or subscription version)
- For SharePoint Server 2016 and 2019: Apply update version 16.0.19725.20210 or later via Microsoft Update/Central Administration
- For SharePoint Server Subscription Edition: Upgrade to version 16.0.19725.20210 or later
- After applying the update, verify the version through Central Administration > System Settings > Manage farm servers
- Test critical SharePoint workflows to ensure functionality is intact post-update
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-2026-20945 — 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-2026-20945 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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