CVE-2025-53690Known exploitationPublic exploitNetwork attack vector

Unauthenticated code execution via forged ViewState

Published Sep 3, 2025 · Updated Feb 26, 2026

ViewState deserialization in Sitecore Experience Manager and Experience Platform 9.0 and earlier allows remote attackers to execute code. The unauthenticated /sitecore/blocked.aspx endpoint deserializes attacker-crafted ViewState because deployments using a published sample ASP.NET machine key cannot distinguish forged state from legitimate state. Exposure requires an ASP.NET page using that sample key; successful requests execute code as the IIS worker process.

CVSS severity9.0
Critical
EPSS probability51.09%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

ViewState deserialization in Sitecore Experience Manager and Experience Platform 9.0 and earlier allows remote attackers to execute code. The unauthenticated /sitecore/blocked.aspx endpoint deserializes attacker-crafted ViewState because deployments using a published sample ASP.NET machine key cannot distinguish forged state from legitimate state. Exposure requires an ASP.NET page using that sample key; successful requests execute code as the IIS worker process.

The record

CVE
CVE-2025-53690
Published
Sep 3, 2025
Updated
Feb 26, 2026
Vendor
Sitecore
Product
Sitecore Experience Manager
Classifications
CWE-502, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 3, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 4, 2025Exploitation reportedCISA Known Exploited Vulnerabilities listing
  3. Feb 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=9.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Sitecore · Sitecore Experience Managerversion=0 <=9.0
Sitecore · Sitecore Experience Platformversion=0 <=9.0

Published CVSS scores

9.0WizCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/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.

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No observations available

Sep 9, 2026Sep 15, 2026
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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