The cyberthreat landscape is evolving rapidly. Attackers are finding new ways to exploit the devices and make the situation vulnerable. Recently, a vulnerability was disclosed in Microsoft’s Windows Snipping Tool, which has created serious issues after the Proof-of-Concept (PoC) exploit was released publicly.
The flaw, CVE-2026-33829, allows attackers to steal Net-NTLM credentials hashes by tricking users into clicking on a malicious link. To help you better understand the Windows Snipping Tool vulnerability and follow the mitigation steps, we’ve curated this blog. Let’s get started!
What is the Windows Snipping Tool Vulnerability (CVE-2026-33829)
According to the official definition in the Microsoft update guide, “Exposure of sensitive information to an unauthorized actor in Windows Snipping Tool to perform spoofing over a network.”
The issue is caused by a malicious deep link that exploits the ms-screensktech URL scheme. An attacker can force the user into clicking a crafted link in a web browser or URL source by embedding it in a web page or email. If the user approves the launch of the link, the URL can cause the computer to connect to an SMB server controlled by the attacker.
This action can give attackers access to NTLM challenge-response data without warning the user. It would disclose the user's NTLMv2 hash to the attacker, who could use it to authenticate the user.
What does NTLM Hash Leak Mean?
NTLM stands for NT LAN Manager and is an older Microsoft authentication protocol that Windows uses in environments, mainly corporate networks. It is a cybersecurity vulnerability in which a user’s sensitive Windows authentication hash is exposed or transmitted to an attacker-controlled server. When your computer tries to connect to a remote resource using NTLM, Windows does not send your password directly. Instead, it sends a hashed response to the server's challenge. The issue is that a hash can be cracked offline with tools like Hashcat, especially when the user uses a weak password.
Why NTLM Hash Leaks Matter?
NTLM is widely used across enterprise environments for authentication and to support legacy apps. While attackers do not obtain plaintext passwords, captured NTLM hashes can still be considered valuable. Some of the potential risks include:
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- Offline password cracking attacks
- Credential thefts
- NTLM relay attacks
- Unauthorized access to the internal system
- In many organizations, a compromised NTLM hash can act as a starting point for a broader intrusion campaign.
Who is Affected with CVE-2026-33829?
The vulnerability affects Windows systems running vulnerable versions of the Snipping Tool on Windows 10 1607, Windows Server 2016, Windows 10 Version 22H2, Windows 10 Version 22H2. Microsoft confirmed customer action for 31 affected platform variants.
Severity and CVSS Score of CVE-2026-33829 in Short
The CVSS 3.1 base score is 4.3, which falls into the medium severity range. The environmental score stands at 3.8, reflecting a low-to-medium overall risk level.
Timeline of the Windows Snipping Tool Vulnerability
The following is the timeline for all the patches in the April 2026 Windows Security update.
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- March 23, 2026: Vulnerability disclosed to Microsoft.
- April 14, 2026: Microsoft releases security patch, public advisory was issued, and PoC was released by BlackArrowSec.
The update removed the vulnerable behavior that allowed attackers to expose NTLM hashes over the network.
Who is at Most Risk?
The following users are at the highest risk of the CVE-2026-33829 vulnerability.
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- Enterprise users operating in Active Directory environments with NTLM authentication are at the highest real-world risk.
- Corporate networks without IT administrators and without automated Patch Tuesday are particularly exposed.
- Users relying on shared document workflows or collaboration platforms are included in the high-probability category.
The PoC Exploit raises the Risk
A public proof-of-concept (PoC) exploit for CVE-2026-33829 greatly amplifies the risk of exploitation. Some time ago, attackers had to have the expertise to build their own exploit for vulnerability. Still, the published PoC shows just how the vulnerability can be exploited to obtain NTLM hashes via a phishing link. This lowers the technical barrier and makes it easier for a wider range of threat actors to exploit this vulnerability.
So far, Microsoft has not reported any successful attempts to exploit vulnerability. Still, the fact that the PoC is available means there is an attack method to exploit. It is time to apply patches and strengthen defenses for organizations, as vulnerabilities with public exploits are often exploited via phishing attacks shortly after publication.
Mitigation Strategies if the Patch Has Been Delayed
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- Restrict NTLM Usage: Make use of Group Policy to allow NTLM auditing and Network security. Block NTLM when Kerberos authentication is available as a fallback.
- User Awareness Training: Educate users about malicious links and phishing campaigns that can expose credentials.
- Block Outbound SMB Traffic: Many organizations do not need SMB access to the internet. Blocking outbound TCP ports 445 and 139 can help stop NTLM credential leakage to external systems.
- Enforce Network Segmentation: Setting proper segmentation reduces the impact of credential theft and opportunities for lateral movement.
Home Mitigation Checklist
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- Open Windows updates. Go to Settings > Windows Updates, then install all available updates.
- Restart your system or device to ensure all patches are applied.
- Make sure you do not click on any type of malicious links that ask you to perform random actions.
- Change your Windows account password if you click on a suspicious link that opens the Snipping Tool before applying this Patch.
Summing It Up!
The Windows Snipping Tool vulnerability CVE-2026-33829 is a reminder that credential theft remains one of the most impactful attack techniques. By exploiting a weakness in the MS-Screensketch URI handler, attackers can capture NTLM hashes through a phishing lure.
Even though Microsoft has shared a fix, organizations should start patching affected systems, reducing NTLM exposure, blocking SMB traffic, and strengthening phishing defenses. With PoC now available, a delay in implementing the remedies could give attackers an easy path to credential compromise and further network intrusion.
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FAQs
Q1. What are the four types of vulnerabilities?
Answer: In cybersecurity, the four primary types of vulnerabilities are network, software, human, and physical.
Q2. What is the impact of the CVE-2026-33829 vulnerability?
Answer: Attackers can access sensitive information and use it to perform spoofing attacks, deceiving users or systems.
Q3. Which systems are affected by CVE-2026-33829?
Answer: The vulnerability affects Windows versions, including Windows 10, and certain Windows server releases if they are not updated.
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