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Microsoft has rolled out its latest Patch Tuesday security update, fixing multiple vulnerabilities, including two actively exploited zero-day vulnerabilities.
The company has urged Windows users and administrators to install these patches immediately to mitigate security risks.
The February 2025 security update addresses 55 vulnerabilities across Windows OS and applications, including critical remote code execution (RCE) and privilege escalation flaws.
Microsoft Fixes Critical Windows Zero-Day Vulnerabilities in February Patch Update
Among the most critical fixes are patches for a Windows zero-day vulnerability affecting the Windows Ancillary Function Driver for WinSock (CVE-2025-21418) and an elevation of privilege bug in Windows Storage (CVE-2025-21391).
These vulnerabilities, which attackers are already exploiting, allow system compromise and unauthorized file deletion, respectively.
Key Security Fixes in the February 2025 Patch Update
Microsoft’s security update includes fixes for a range of vulnerabilities, classified as Critical, Important, and Moderate in severity. Below are some of the most concerning security issues addressed:
| CVE ID | Vulnerability Type | Impact |
|---|---|---|
| CVE-2025-21418 | WinSock Elevation of Privilege | Grants SYSTEM privileges to attackers |
| CVE-2025-21391 | Windows Storage Privilege Escalation | Allows deletion of targeted system files |
| CVE-2025-21376 | LDAP Remote Code Execution | Wormable between affected servers |
| CVE-2025-21387 | Microsoft Excel RCE | Exploitable via Preview Pane |
Urgent Patches for Actively Exploited Vulnerabilities
One of the most dangerous flaws patched this month is CVE-2025-21418, a Windows zero-day vulnerability in the Ancillary Function Driver for WinSock. Attackers can exploit this bug to escalate privileges and gain SYSTEM-level access.
Once inside, they can execute malicious code with full administrative control over the affected system.
Another alarming issue is CVE-2025-21391, a privilege escalation flaw in Windows Storage. This bug enables attackers to delete crucial system files, potentially causing disruptions or system crashes.
Microsoft strongly advises immediate patching to prevent exploitation.
A Wormable Threat: LDAP Remote Code Execution Flaw (CVE-2025-21376)
Security experts are also sounding the alarm over CVE-2025-21376, a remote code execution (RCE) vulnerability in the Windows Lightweight Directory Access Protocol (LDAP).
This bug is particularly dangerous because it is considered wormable, meaning it can spread between vulnerable LDAP servers without user interaction.
According to Microsoft, an unauthenticated attacker could send a specially crafted request to an LDAP server, triggering a buffer overflow that allows remote code execution.
Because of its high exploitation potential, organizations are urged to apply this patch without delay.
Microsoft Excel Preview Pane Exploit (CVE-2025-21387)
Microsoft has also addressed multiple vulnerabilities affecting its Office suite, particularly Excel. The most severe, CVE-2025-21387, is a remote code execution bug that can be triggered simply by previewing a malicious Excel file in Outlook’s Preview Pane.
Since user interaction isn’t required for a successful attack, this makes the flaw particularly dangerous.
Additional Vulnerabilities to Watch
Besides the actively exploited zero-days, Microsoft has patched other publicly disclosed vulnerabilities, including:
- CVE-2025-21194 – Security feature bypass bug in Microsoft Surface.
- CVE-2025-21377 – NTLM Hash spoofing vulnerability that exposes users’ authentication data.
- CVE-2025-21179 – DHCP service denial-of-service (DoS) vulnerability.
Microsoft’s Lack of Indicators of Compromise (IOCs)
Despite the severity of these security flaws, Microsoft has not provided Indicators of Compromise (IOCs) or telemetry data to help cybersecurity teams detect potential exploitation attempts.
This has left IT administrators reliant on third-party threat intelligence to track active attacks.
Actionable Recommendations for Users and IT Teams
To protect against these vulnerabilities, Microsoft recommends the following steps:
- Install patches immediately – Update Windows OS and Microsoft applications via Windows Update.
- Enable automatic updates – Ensure security patches are applied as soon as they are released.
- Monitor security logs – Watch for signs of unauthorized access or system modifications.
- Restrict LDAP traffic – If not required, consider disabling external access to LDAP servers.
- Be cautious with email attachments – Avoid opening suspicious Microsoft Excel files, especially in Preview Pane.
Final Thoughts
Microsoft’s February 2025 Patch Tuesday brings essential security fixes, including patches for two actively exploited zero-day vulnerabilities.
The Windows zero-day vulnerability affecting WinSock and the wormable LDAP bug pose serious threats to organizations and individuals alike.
Users should apply these updates immediately to prevent system compromise and mitigate cyber risks.
For the latest security updates and detailed patch information, visit Microsoft’s official security bulletin or check with trusted cybersecurity sources.
