Critical SharePoint RCE Vulnerability CVE-2025-53770 Actively Exploited: What You Need to Do Now
A severe vulnerability has been identified in multiple versions of Microsoft SharePoint Server, tracked as CVE-2025-53770. This is not a theoretical threat; security researchers and Microsoft have confirmed that this flaw is actively being exploited in the wild. System administrators must take immediate action to mitigate the risk and protect their environments.
This critical flaw allows for Remote Code Execution (RCE), which is one of the most serious types of vulnerabilities. It enables an unauthenticated attacker to run arbitrary code on a target SharePoint server, effectively giving them complete control.
What is the Impact of CVE-2025-53770?
The successful exploitation of CVE-2025-53770 can have devastating consequences. An attacker who gains control of a SharePoint server can:
- Steal, modify, or delete sensitive corporate data. SharePoint often houses critical business documents, intellectual property, and personal identifiable information (PII).
- Install ransomware or other malware. The compromised server can be used as a beachhead to launch further attacks across your entire network.
- Create backdoors for persistent access. Attackers can implant hidden tools to maintain access long after the initial breach.
- Disrupt business operations by taking the SharePoint service offline or corrupting its data.
Because the vulnerability allows for unauthenticated access, an attacker needs no special permissions or credentials to launch an attack. They only need network access to the vulnerable SharePoint server, making internet-facing servers exceptionally high-risk.
Which SharePoint Versions Are Affected?
This vulnerability impacts on-premises installations of SharePoint Server. According to the latest security bulletins, the following versions are confirmed to be vulnerable:
- Microsoft SharePoint Server 2016
- Microsoft SharePoint Server 2019
- Microsoft SharePoint Server Subscription Edition
It is important to note that SharePoint Online is not affected by this specific vulnerability, as Microsoft manages the security and patching of its cloud infrastructure directly.
Immediate Steps to Protect Your Organization
Due to the active exploitation of this flaw, time is of the essence. Organizations using the affected SharePoint versions should implement the following security measures immediately.
1. Patch Immediately
Microsoft has released security updates to address CVE-2025-53770. This is the most critical step you can take. Applying the official security patch is the only way to fully remediate the vulnerability. Do not delay deployment. Ensure you are applying the correct cumulative update (CU) for your specific SharePoint version and patch level.
2. Hunt for Indicators of Compromise (IoCs)
Since this flaw is already being exploited, you must assume your system may have been compromised. Your security team should actively hunt for signs of a breach. Key IoCs include:
- Unusual child processes spawning from the SharePoint worker process (
w3wp.exe), such ascmd.exe,powershell.exe, orcertutil.exe. - Suspicious file creation in SharePoint-related directories, especially the creation of web shells (
.aspxfiles) or executable files (.exe,.dll). - Unexpected outbound network traffic from your SharePoint servers to unknown IP addresses.
- New, unauthorized user accounts created on the server or within the domain.
3. Restrict Access as a Temporary Mitigation
If you cannot patch immediately, consider implementing temporary mitigations. Restrict access to the SharePoint web application at the network perimeter. If your SharePoint site must be internet-facing, limit access to trusted IP addresses only until patching is complete. While not a substitute for patching, this can reduce the attack surface.
4. Review and Harden Your Security Posture
A high-severity event like this serves as a critical reminder of the importance of defense-in-depth. Use this opportunity to review your overall security posture. Ensure that your SharePoint servers are hardened according to security best practices, that you have robust monitoring and logging in place, and that your incident response plan is up to date.
In conclusion, CVE-2025-53770 represents a clear and present danger to organizations running on-premises SharePoint. The combination of a critical RCE flaw and active exploitation requires a swift and decisive response. Prioritize patching, investigate for potential compromise, and use this event to strengthen your long-term security strategy.
Source: https://securityaffairs.com/180182/hacking/sharepoint-zero-day-cve-2025-53770-actively-exploited-in-the-wild.html
