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CVE-2025-49706 is an improper authentication vulnerability (CWE-287) in Microsoft SharePoint Server’s ToolPane endpoint. It allows an unauthorized attacker to perform spoofing over a network. The vulnerability arises because SharePoint fails to properly validate the `Referer` HTTP header; it trusts a crafted `Referer` value that points to /layouts/SignOut.aspx. By forging a single HTTP request containing this spoofed `Referer` header, an attacker can bypass authentication mechanisms and access protected SharePoint APIs without any credentials or user interaction.
The flaw is classified as Improper Authentication and can be exploited remotely with low attack complexity, requiring no privileges and no user interaction. The vulnerability affects SharePoint Server 2016, 2019, and Subscription Edition (versions < 16.0.18526.20424). It was publicly disclosed at Pwn2Own Berlin 2025 and is part of the “ToolShell” attack chain, often combined with CVE-2025-49704 (remote code execution) to achieve full compromise.
The impact is rated Medium with a CVSS base score of 6.5, but active exploitation has been confirmed in the wild. A proof-of-concept (PoC) is publicly available, and threat actors are chaining this spoofing flaw with other vulnerabilities to deploy web shells and escalate privileges. Microsoft released a security update on July 8, 2025 to patch the issue.
DailyCVE Form
Platform: Microsoft SharePoint Server
Version: 2016,2019,Sub<16.0.18526.20424
Vulnerability: Spoofing (Improper Authentication)
Severity: Medium
Date: 08/07/2025
Prediction: Already patched (July 8, 2025)
What Undercode Say:
Simulate a spoofed request to the vulnerable ToolPane endpoint curl -X POST "http://target-sharepoint/_layouts/15/ToolPane.aspx?DisplayMode=Edit" \ -H "Referer: http://target-sharepoint/_layouts/SignOut.aspx" \ -H "Content-Type: application/x-www-form-urlencoded" \ -d "param=value"
Python PoC snippet (educational only)
import requests
url = "http://vulnerable-sharepoint/_layouts/15/ToolPane.aspx"
headers = {"Referer": "http://vulnerable-sharepoint/_layouts/SignOut.aspx"}
response = requests.post(url, headers=headers)
print(response.status_code)
Exploit:
- Send a forged `POST` request to `/ToolPane.aspx` with a `Referer` header pointing to
/SignOut.aspx. - SharePoint erroneously treats the request as authenticated, granting access to protected APIs.
- Chaining with CVE-2025-49704 allows uploading a web shell (e.g.,
spinstall0.aspx) and executing system commands.
Protection from this CVE:
- Apply Microsoft’s July 8, 2025 security update immediately.
- Block unauthenticated access to `/_layouts/15/ToolPane.aspx` via WAF or reverse proxy.
- Monitor for suspicious `Referer` headers pointing to
/layouts/SignOut.aspx. - Regenerate cryptographic machine keys if compromise is suspected.
Impact:
- Unauthorized access to SharePoint APIs and sensitive data.
- Impersonation of legitimate users, leading to privilege escalation.
- Full server compromise when chained with RCE vulnerabilities (ToolShell campaign).
- Data exfiltration, persistent backdoors, and lateral movement within the network.
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Sources:
Reported By: www.cve.org
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