Microsoft SharePoint Improper Authentication (CVE-2025-49706)

Historical catalog analysis: CISA added this entry on July 22, 2025. The entry reflects catalog information retrieved on August 31, 2026, not a snapshot archived on the inclusion date. Check current vendor guidance before acting.

What the vulnerability is

CVE-2025-49706 is an improper authentication vulnerability (CWE-287) affecting Microsoft SharePoint. The flaw allows an authorized attacker to perform network-based spoofing, which could enable them to view sensitive information and modify disclosed data. This vulnerability can be chained with CVE-2025-49704. Furthermore, a patch bypass identified as CVE-2025-53771 exists; updates addressing CVE-2025-53771 provide more robust protection than the initial fixes for CVE-2025-49706.

Exposure and applicability

This vulnerability applies to on-premises Microsoft SharePoint environments. Organizations running supported versions are susceptible unless updated. A critical exposure path exists for organizations utilizing public-facing instances of SharePoint Server that have reached end-of-life (EOL) or end-of-service (EOS), specifically including SharePoint Server 2013 and earlier versions.

Potential breach-prevention strategy

The source reports that this vulnerability is known to be used in ransomware campaigns. The reported entry path involves an authorized attacker leveraging improper authentication to spoof identity and access sensitive data, though the specific method of initial authorization remains unknown.

Our analysis suggests a similar breach could have been mitigated through the following prioritized actions:

1. Decommission EOL/EOS Assets: Public-facing legacy versions (SharePoint 2013 and earlier) lack vendor support and are high-risk entry points.

   • Responsible Role: Infrastructure Owner / System Administrator.
   • Verification: Network scan to confirm the absence of public-facing EOL SharePoint listeners.
   • Goal: Prevent initial access via unsupported software.

2. Prioritize Robust Patching (CVE-2025-53771): Because CVE-2025-49706 has a known patch bypass, applying the more recent updates for CVE-2025-53771 is critical.

   • Responsible Role: Vulnerability Management Team.
   • Verification: Verification of installed update versions against vendor-specified robust protection baselines.
   • Goal: Prevent initial access by closing the authentication flaw and its bypass.

3. Restrict Network Exposure: Limit public access to SharePoint interfaces to only those strictly required for business operations.

   • Responsible Role: Network Security Engineer.
   • Verification: Review of firewall rules and ACLs restricting access to authorized IP ranges.
   • Goal: Limit the attack surface available to potential spoofing attempts.

These actions are feasible before an incident occurs. However, residual risk remains if attackers leverage other chained vulnerabilities or valid credentials that bypass these specific authentication controls.

Remediation priorities

Remediation should be prioritized based on asset exposure and version support:
* Immediate Action: Disconnect all public-facing SharePoint Server versions that are EOL or EOS (including 2013 and earlier).
* High Priority: For supported versions, apply vendor updates. Defenders should prioritize the updates associated with CVE-2025-53771 over those for CVE-2025-49706 alone to ensure more robust protection.

How to validate remediation

To verify that exposure has been reduced, defenders should move beyond simple version checks:
* Connectivity Validation: Confirm that EOL/EOS versions are no longer reachable from the public internet via network mapping.
* Update Verification: Cross-reference installed patches with vendor documentation specifically for CVE-2025-53771 to ensure the bypass is addressed.
* Configuration Audit: Review authentication logs for unauthorized spoofing attempts or anomalous behavior by authorized accounts that may indicate a failed remediation.

Limits and open questions

It remains unclear what specific level of authorization is required for an attacker to exploit this flaw. Additionally, while updating to the latest version reduces risk, it does not eliminate the possibility of other vulnerabilities being chained with this flaw. The effectiveness of these mitigations depends on the complete removal of legacy public-facing instances and the application of the most recent robust updates rather than early iterations of the patch.

Source and editorial note

CVE-2025-49706: Microsoft SharePoint Improper Authentication Vulnerability · Source date: July 22, 2025 · Retrieved August 31, 2026.

Material facts are tied to the cited primary source. Recommendations are independent defensive analysis unless attributed to the source. Confirm consequential decisions against current authoritative guidance.

Archive date: July 25, 2025. The displayed post date is assigned three days after the source date to organize this retrospective archive; it does not mean this site published the analysis then. First published by this site: October 08, 2026 at 00:09 UTC.

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