CVE-2021-42237
Published: 05 November 2021
Summary
CVE-2021-42237 is a critical-severity Deserialization of Untrusted Data (CWE-502) vulnerability in Sitecore Experience Platform. Its CVSS base score is 9.8 (Critical).
Operationally, ranked in the top 0.0% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2021-42237 is an insecure deserialization vulnerability, tracked under CWE-502, that affects Sitecore Experience Platform (XP) versions from 7.5 Initial Release through 8.2 Update-7. The flaw permits remote command execution on the underlying host system and carries a CVSS v3.1 base score of 9.8.
An unauthenticated attacker with network access can send a crafted serialized object to the affected Sitecore instance, triggering deserialization that results in arbitrary command execution. No special configuration or credentials are required, enabling an attacker to obtain full control over the server.
Public references include a Sitecore knowledge-base article (KB1000776) that addresses remediation, along with technical write-ups and proof-of-concept code demonstrating the issue. The vulnerability was publicly disclosed in November 2021 with accompanying exploit material.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-29215
Vulnerability details
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(s)
- KEV Date Added
- 25 March 2022
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly blocks the crafted serialized object from being deserialized by enforcing validation of all untrusted input before processing.
Requires prompt application of the vendor patch (KB1000776) that eliminates the insecure deserialization code path in affected Sitecore versions.
Can detect or block the malicious payload that results from successful deserialization leading to remote command execution.