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CVE-2021-42237

9.8, critical Known exploited Used in ransomware

Sitecore XP Remote Command Execution Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab) CISA KEV catalogue (opens in a new tab)
CVSS
9.8, critical critical CVSS v3.1
EPSS, next 30 days
98% higher than 99.9% of scored CVEs
Exploitation
Confirmed in the wild
Published
5 Nov 20214 years ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 25 Mar 2022 and links it to ransomware activity. US federal agencies had to remediate by 15 Apr 2022, a deadline that has passed.

Required action. Apply updates per vendor instructions.

Description

Sitecore XP 7.5 Initial Release to Sitecore XP 8.2 Update-7 is vulnerable to an insecure deserialization attack where it is possible to achieve remote command execution on the machine. No authentication or special configuration is required to exploit this vulnerability.

Details

Vendor
Sitecore
Product
Experience Platform
Weakness
CWE-502 (opens in a new tab)
Status
Analyzed
Updated
9 Jul 2026
Assigner
cve@mitre.org

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

References 4

Exploit code 2

Advisories 1

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Sitecore CVEs

Every Sitecore CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2025-53690 Sitecore Multiple Products Deserialization of Untrusted Data Vulnerability KEV EPSS 61% 9, critical
  • CVE-2019-9874 Sitecore CMS and Experience Platform (XP) Deserialization Vulnerability KEV EPSS 84% 9.8, critical
  • CVE-2019-9875 Sitecore CMS and Experience Platform (XP) Deserialization Vulnerability KEV EPSS 14% 8.8, high

Beyond this page

Is CVE-2021-42237 in your network?

This page tells you how dangerous CVE-2021-42237 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2021-42237 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2021-42237 comes with the devices to patch.

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  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.