Week 18 – Behind the Mask: SharePoint Spoofing in the Wild
27 Apr – 03 May 2026
In this week’s CVE of the Week we’ll be looking CVE-2025-32201, a spoofing vulnerability in Microsoft SharePoint Server caused by improper input validation, with a CVSS score of 6.5
It allows a remote, unauthenticated attacker to impersonate trusted users or content over the network. Despite its medium-severity vulnerability, the flaw has been actively exploited in the wild and added to CISA’s KEV catalog, elevating its operational risk.
Root cause of the CVE
The vulnerability stems from improper input validation (CWE-20) in SharePoint’s request-handling logic. Specifically, the application fails to adequately validate user-controlled input, enabling attackers to inject crafted data that manipulates system behavior.
Why is it critical in practice and the impact of the CVE
Successful exploitation enables attackers to:
- Spoof trusted users or services
- Access, or expose sensitive information
- Modify or manipulate content within SharePoint
- Potentially facilitate phishing or redirection attacks
- As well as lateral movement more effective in enterprise environments
Key contributing factors:
- Network-accessible attack surface (remote exploitation)
- No authentication or user interaction required
- Low attack complexity
- Widespread use of SharePoint in enterprise environments
- Delayed patch adoption (thousands of exposed systems still vulnerable)
Condition of the exploit:
Exploitation is network-based and can be triggered by sending specially crafted requests to a vulnerable SharePoint instance. The attack requires no privileges and no user interaction, making it highly scalable for opportunistic or targeted campaigns.
Affected versions:
- SharePoint Server 2016
- SharePoint Server 2019
- SharePoint Server Subscription Edition
Mitigation / remediation / workaround solutions:
- Apply Microsoft’s April 2026 security updates immediately
- Restrict external exposure of SharePoint instances
- Monitor logs for anomalous requests or spoofing indicators
- Implement web application firewall (WAF) protection as a temporary control
For More Information:
https://cybersecuritynews.com/1370-sharepoint-servers-vulnerable/
https://www.cve.org/CVERecord?id=CVE-2026-32201
https://nvd.nist.gov/vuln/detail/CVE-2026-32201
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-32201
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