Is CVE-2021-42237 in the CISA KEV catalog?

Yes. CVE-2021-42237 is on the CISA Known Exploited Vulnerabilities list, added 2022-03-25, and has known ransomware campaign use.

What is the CVSS severity of CVE-2021-42237?

CVE-2021-42237 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2021-42237?

CVE-2021-42237 has an EPSS score of 97.90% (100th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2021-42237?

No published fix for CVE-2021-42237 has been found yet. It is on the CISA Known Exploited Vulnerabilities list; federal agencies must remediate by 2022-04-15. Apply the vendor's mitigations per CISA's guidance.

CVE & CISA-KEV Catalog

CVE-2021-42237

CRITICALCISA KEVEPSS 100th pctl

9.8

CVSS v3

NVD

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.

CWE-502Deserialization of Untrusted Data

How to fix

Actively exploited, no published fix found yet

CISA required action: Apply updates per vendor instructions.

Federal remediation due: 2022-04-15

Known ransomware campaign use

Mitigation guidance may be in the linked vendor advisories in the References section below.

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CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

97.90%probability of exploitation in 30 days

100thpercentile

Very high risk: more likely to be exploited than 100% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Sitecore XP Remote Command Execution Vulnerability

Sitcore XP contains an insecure deserialization vulnerability which can allow for remote code execution.

Apply updates per vendor instructions.

Remediation due: 2022-04-15

Associated with ransomware campaigns

References

Exploit1

blog.assetnote.io

Vendor Advisory1

support.sitecore.com

Third-Party Advisory1

packetstormsecurity.com

Government Resource1

cisa.gov

Related Vulnerabilities

Other CWE-502 (Deserialization of Untrusted Data) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-0669	High	7.2	100%	KEV + Ransom	Fix
CVE-2021-44228	Critical	10.0	100%	KEV + Ransom	Fix
CVE-2021-35464	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2023-29300	Critical	9.8	100%	KEV + Ransom	-
CVE-2025-53770	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2022-41082	High	8.0	100%	KEV + Ransom	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-09.