CVE-2021-42237Known exploitationPublic exploitNetwork attack vector

Unauthenticated code execution via unsafe XML deserialization

Published Nov 5, 2021 · Updated Jul 9, 2026

Insecure deserialization in Sitecore XP 7.5 Initial Release through 8.2 Update-7 allows remote attackers to execute arbitrary commands. The unauthenticated Report.ashx handler passes attacker-controlled XML parameter objects to NetDataContractSerializer.ReadObject, enabling a gadget chain. No authentication or special configuration is required, and successful exploitation runs commands with the Sitecore application process privileges.

CVSS severity9.8
Critical
EPSS probability97.90%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insecure deserialization in Sitecore XP 7.5 Initial Release through 8.2 Update-7 allows remote attackers to execute arbitrary commands. The unauthenticated Report.ashx handler passes attacker-controlled XML parameter objects to NetDataContractSerializer.ReadObject, enabling a gadget chain. No authentication or special configuration is required, and successful exploitation runs commands with the Sitecore application process privileges.

The record

CVE
CVE-2021-42237
Published
Nov 5, 2021
Updated
Jul 9, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-502, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 5, 2021CVE publishedPublication date reported by the CVE source.
  2. Mar 25, 2022Exploitation reportedCISA Known Exploited Vulnerabilities catalog listing
  3. Jul 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

10.0NIST NVDAV:N/AC:L/Au:N/C:C/I:C/A:C
9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsShadowserver observations through Sep 15, 2026. Gaps indicate unavailable data.
Sep 9, 2026Sep 15, 2026
View daily counts
Reporting dayUnique IPs
Sep 9, 2026Unavailable
Sep 10, 2026Unavailable
Sep 11, 2026Unavailable
Sep 12, 2026Unavailable
Sep 13, 2026Unavailable
Sep 14, 20261
Sep 15, 2026Unavailable
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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