What it is
CVE-2021-42237 is an unauthenticated vulnerability affecting Sitecore Sitecore XP. Sitecore XP 7.5 Initial Release to Sitecore XP 8.2 Update-7 is vulnerable to an insecure deserialization attack where it is possible...
Vulnerability report
Exploited in the wild
Confirmed confidence
In CISA KEV
CVE-2021-42237
Sitecore XP Deserialization
Sitecore / Sitecore XP
- Severity
- CVSS 9.8 · Critical
- Confidence
- Confirmed
- Exploit status
- Exploited in the wild
- EPSS
- 97.9%
- First observed
- —
- Last observed
- —
Decision summary
What security teams need to know first
Direct answers before the deeper technical record.
Is it exploited?
Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.
Who is affected?
Sitecore / Sitecore XP.
What should we do?
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
Overview
Sitecore XP Deserialization
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.
- Published
- 05 Nov 2021
- Exploitation Reported
- 25 Mar 2022
- Attack vector
- Remote
- Complexity
- Low
- Privileges
- None
- User interaction
- None
Tags
cisa
metasploit
malware
nuclei_scanner
ransomware
CVE References
- CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2021-42237
- support.sitecore.com/kb support.sitecore.com · CVE Record https://support.sitecore.com/kb?id=kb_article_view&sysparm_article=KB...
- blog.assetnote.io/2021/11/02/sitecore-rce blog.assetnote.io · CVE Record https://blog.assetnote.io/2021/11/02/sitecore-rce/
- packetstormsecurity.com/files/164988/Sitecore-Experience-Platform-XP... packetstormsecurity.com · CVE Record http://packetstormsecurity.com/files/164988/Sitecore-Experience-Platf...
Exploitation evidence
Why KEV Intelligence marks this CVE as exploited
Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.
Exploited in the wild
CISA
Independent exploitation attestation added to the KEV Intelligence record.
Used in malware
CISA
Malware families have been linked to exploitation of this CVE.
Proof of concept available
GitHub
Public scanner or PoC coverage increases practical exploitability.
Known exploited vulnerability sources
Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.
Learn about Pro API access| Source | Added |
|---|---|
| CISA First | 2022-03-25 00:00 UTC |
| CVE | 2026-07-05 00:30 UTC |
| The Shadowserver | 2026-07-08 00:00 UTC |
Detection
Operational artifacts and observed signals
Make the evidence actionable in scanner, SOC, and edge-control workflows.
Observed signals
- Request targets
- 0
- User-Agents
- 0
Raw values available in Pro and Enterprise.
Scanner coverage
Metasploit template detected 28 Apr 2025.
View Metasploit template (opens in new tab)Virtual patch status
No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.
Learn about virtual patches →Scanner Artifacts
Scanner and exploit-framework references linked to this CVE.
| Scanner | Reference | Detected |
|---|---|---|
| Metasploit | https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/windows/http/sitecore_xp_cve_2021_42237.rb | 28 Apr 2025 |
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-42237.yaml | 25 Apr 2025 |
Risk and context
Severity, weaknesses, and research context
CVSS v3.1
9.8
Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
97.9%
Weaknesses
All CVSS Scores
CVSS v3.1
9.8
Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v2.0
10.0
High
AV:N/AC:L/Au:N/C:C/I:C/A:C
Potential Proof of Concepts
These PoCs are unverified and could contain malware. Use at your own risk.
Sitecore Experience Platform Pre-Auth RCE
nuclei · Created Unknown
Timeline
From disclosure to observed exploitation
-
KEV confirmed by The Shadowserver
Exploitation attested by an external source
-
KEV confirmed by CVE
Exploitation attested by an external source
-
Metasploit module available
Exploit module available
-
Public PoC available
Public proof-of-concept code published
-
Nuclei template available
Scanner coverage available
-
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
First public exploitation report
Exploit observed in malware
-
CVE published
Vulnerability disclosed publicly
-
CVE ID reserved
Identifier reserved by the CNA
Pro API
Automate this intelligence
Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
- Evidence confidence and provenance
- First-party sensor telemetry
- PoC and scanner references
- Affected versions and enrichment
- Automation-ready JSON delivery
GET /api/v2/pro/kevs/CVE-2021-42237
Free JSON includes basic KEV fields{
"cve_id": "CVE-2021-42237",
"confidence": "Confirmed",
"cvss_score": 9.8,
"cvss_estimated": false,
"epss_score": 0.97904,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "attempts": 0, "sensors": 0 }
}Early warning alerts
Get alerts on high-impact exploitation
Receive curator-selected alerts when exploitation activity warrants attention. Each alert includes the evidence and context needed to decide what requires attention now.