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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 16 Apr 2025.
CmsApplication · Sitecore

CVE-2019-9875

HIGH · 8.8 CVSS v3.1 Published 2019-05-31
Fix available
A fix is available. Upgrade to after 9.1 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Public exploit Remotely reachable Zero-click Patch available

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
Deserialization of Untrusted Data in the anti CSRF module in Sitecore through 9.1 allows an authenticated attacker to execute arbitrary code by sending a serialized .NET object in an HTTP POST parameter.

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

This is an insecure deserialization vulnerability in Sitecore's anti-CSRF module. An authenticated attacker can send a malicious serialized .NET object via HTTP POST parameter to the affected module, triggering arbitrary code execution on the server due to unsafe deserialization of untrusted data.

MitigationUpgrade Sitecore to a version beyond 9.1 that includes the security patch, or apply any available hotfix from Sitecore for this vulnerability. As a compensating control, restrict network access to administrative endpoints and monitor for serialized object uploads.

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
CmsApplication
Affected:<= 9.1

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

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. Identify the installed Sitecore version
    Locate the Sitecore installation directory and check the version information in the Sitecore configuration files or the /sitecore/admin/showconfig.aspx admin page. The version is typically visible in the Sitecore.Shell.Applications.Information class assembly or the version attribute in the web.config.
    Affected if The installed version is 9.1 or any version lower than 9.1 (versions through 9.1).
  2. Confirm the anti-CSRF module is enabled
    Inspect the Sitecore configuration files (including the web.config and Sitecore config files in the App_Config folder) for the presence and status of the anti-CSRF module configuration. Look for configuration sections related to anti-CSRF or CSRF protection.
    Affected if The anti-CSRF module is present and enabled in the Sitecore configuration.
  3. Verify the vulnerable POST endpoint is exposed
    Check if the Sitecore anti-CSRF endpoint that accepts serialized .NET objects via HTTP POST is accessible. This endpoint is typically reachable through the site and accepts POST requests with serialized content.
    Affected if The anti-CSRF endpoint accepts unauthenticated or authenticated user POST requests containing serialized .NET objects.

You are affected if your Sitecore installation is version 9.1 or lower AND the anti-CSRF module is enabled AND the vulnerable endpoint is accessible to attackers.

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 a release after 9.1
Vendor patch www.synacktiv.com →
Interim mitigation

Upgrade Sitecore to a version beyond 9.1 that includes the security patch, or apply any available hotfix from Sitecore for this vulnerability. As a compensating control, restrict network access to administrative endpoints and monitor for serialized object uploads.

Recommended fix Moderate confidence

Sitecore 9.2 or later (or the latest available Sitecore XP release)

  1. Identify current Sitecore version by checking the /sitecore/admin/showconfig.aspx page or Sitecore.Configuration.CmsInformation class
  2. Backup the Sitecore databases and files before any upgrade
  3. Ensure the target environment meets the prerequisites for the new Sitecore version
  4. Upgrade Sitecore from version 9.1 or lower to Sitecore 9.2 or later
  5. After upgrade, verify the anti-CSRF module is functioning correctly by testing form submissions
  6. Test critical workflows to ensure the upgrade did not break existing functionality
Caveat Upgrading from 9.1 to 9.2 may require configuration adjustments and index rebuilding; review Sitecore 9.2 release notes for breaking changes and migration steps

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

Fix this in Cms Exploited in the wild — priority engagement
  • Consultation8.0 h
  • Implementation24.0 h
  • Testing12.0 h
  • Review / QA8.0 h
52.0 hours of engineering $9,160
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $14,656.

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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-2019-9875 in production — separate from our analysis above.

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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