January 2025 Patch Tuesday: Critical Updates KB5050009 & KB5050021 for Windows 11

Welcome to the new year of Patch Tuesday madness, Windows Forum fam! January 2025 starts off with a bang—for system administrators and cybersecurity teams, that is. Microsoft's first Patch Tuesday for the year has rolled out a swath of updates aimed at tackling some critical vulnerabilities, including those that malicious actors have already exploited in the wild. If this hasn't prodded you to patch your systems yet, allow me to break down why you should make it priority numero uno.
Let’s dive into the technical weeds to find out what’s going on, how these issues might affect you, and what you can do to protect your systems.

---

Hyper-V: Under Siege by Zero-Days​

Microsoft’s Hyper-V, the super-powerful hypervisor that makes cloud computing and virtual machines happen, is one of the stars of this month’s patchathon. But alas, it's for all the wrong reasons. Three severe vulnerabilities (CVE-2025-21333, CVE-2025-21334, CVE-2025-21335) have been flagged as actively exploited in the wild. These flaws—rated as “Important” with CVSS scores of 7.8—come straight out of a security engineer’s nightmare.

What Are These Vulnerabilities About?​

• Type of Bugs: Two of these are "use-after-free" vulnerabilities, and one is a "heap buffer overflow" issue. These bugs crop up where memory isn't handled properly. When exploited, this can allow attackers, or even rogue software already on the machine, to escalate their privileges to SYSTEM-level access.
• So... What’s Happening?:
• A use-after-free involves attackers exploiting memory that's already been freed. Imagine renting out a room that's simultaneously being used by its previous tenant—only it’s your system’s memory and malicious code is moving in!
• A heap buffer overflow works by shoving more data into memory than it was designed to hold, causing a spillover into other adjacent memory, which attackers then abuse to gain control.

Critical Context​

While these flaws don't offer guest-to-host escapes in virtualization setups (thankfully!), the thought of malware or a rogue insider cruising around with SYSTEM-level access should still send chills down your spine. Hyper-V powers critical enterprise environments, so patching here is non-negotiable.

---

Remote Code Execution Galore​

If Hyper-V’s woes weren’t enough, this Patch Tuesday also comes with three "critical" vulnerabilities rated a terrifying 9.8/10. Listed below are the culprits and why they should be on your radar.

CVE-2025-21311 (NTLMv1 Poison)​

• Type of Vulnerability: Elevation-of-privilege exploit.
• Problem: NTLMv1 authentication—an ancient relic from the Windows past—got hit. Attackers can exploit this over the network to gain administrative privileges.
• Fix: Microsoft offers a patch but recommends upgrading your system settings as further mitigation. Set LmCompatibilityLevel = 5 to block NTLMv1 entirely while still keeping NTLMv2 functional.

Why It Matters: NTLMv1 persists in older legacy systems, which some businesses refuse to let go of. Modern environments should have phased out NTLMv1 already. If you fall into this category, it’s time to get rid of that ticking time bomb.

CVE-2025-21307 (Windows PGM RCE)​

This one’s for network admins—particularly those dabbling with Windows Pragmatic General Multicast (PGM) for data broadcasting.

• Risk: All an attacker needs here is a single program listening on a PGM port, and BAM! Crafted packets sent to this open port can trigger remote code execution (RCE).
• Reality Check: Most admins know not to expose PGM to public internet traffic. But for those who ignored that wisdom, this bug delivers major pain.

---

A Familiar Enemy: OLE Is Back​

CVE-2025-21298 hits the Object Linking and Embedding (OLE) framework. Everyone’s favorite mechanism for embedding documents into emails and applications has been weaponized once again. Here's the kicker: A specially crafted email is all it takes—open it, and attackers could execute remote malicious code.

---

Excel Vulnerabilities: A Classic Malware Playground​

Just when you thought spreadsheets weren’t dangerous, CVE-2025-21362 and CVE-2025-21354 bring threats to the boardroom. Both vulnerabilities allow execution of malicious code if a user opens a compromised Excel file. No tricks or admin privileges are needed.
Why is this especially alarming? Social engineering. Attackers will likely email phishing-laden Excel files to unsuspecting businesses because… well, who doesn’t trust spreadsheets?

---

Remote Desktop & SPNEGO: New Queues for Disaster​

Bad actors are always fishing for weaknesses in Remote Desktop Protocol (RDP), and two race-condition bugs (CVE-2025-21309, CVE-2025-21297) just made their job easier. Once exploited, it’s game over as attackers can potentially execute arbitrary code via use-after-free scenarios.
Additionally, the spiffy-named SPNEGO NEGOEX protocol—one of Microsoft’s go-to authentication methods—has CVE-2025-21295. Exploiting it gives attackers remote code execution power by essentially manipulating the way systems process negotiation for authentication.

---

What’s The Game Plan?​

• Apply Updates Immediately: Prioritize the Hyper-V, NTLMv1, and Excel patches. The first two require immediate action if you're running Hyper-V in any professional capacity or still supporting legacy systems.
• Hardening NTLM Configurations:
• Make sure NTLMv1 is turned off (LmCompatibilityLevel = 5).
• Consider scouring systems for unexpected PGM usage.
• Prevent Social Engineering:
• Educate employees on the risks of opening unsolicited Excel documents.
• Leverage email filtering tools to weed out suspicious attachments.

---

Other Updates to Watch​

While Microsoft dominates the spotlight, don’t sleep on other vendors joining the chaotic January rush:

• Adobe patched Photoshop, Illustrator, Animate, and Substance3D Stager for critical vulnerabilities—get those updates if you’re rocking creative suites.
• Cisco has issues with Snort (its intrusion detection system), but these are medium-severity flaws primarily affecting macOS solutions.

---

Final Thoughts​

January 2025’s Patch Tuesday highlights memory safety flaws, elevated risks stemming from legacy technologies, and a reminder that basic IT hygiene can save you from catastrophic headaches. Whether you're guarding a network full of virtual machines or running RDP to support remote workers, take action today to prevent becoming tomorrow's exploit statistic.
What’s your go-to Patch Tuesday ritual? Let us know in the forum comments! Were the updates smooth—are there concerns lingering? Let’s hash it out!
Stay safe out there, WindowsForum family. Until next time: Patch, plan, and problem-solve!

---

Source: The Register Microsoft fixes exploited Hyper-V privilege escalation flaws

In a measured yet critical update for Windows users and IT professionals alike, Microsoft’s February 2025 Patch Tuesday has rolled out fixes for 57 vulnerabilities. While this update isn’t as massive as the January release—which tackled a whopping 159 issues—it nonetheless targets several high-priority security flaws, including three critical vulnerabilities already exploited in the wild.

---

A Closer Look at the Critical Vulnerabilities​

1. Windows Storage Elevation-of-Privilege (EOP)​

One of the standout fixes in this update is for a Windows storage EOP vulnerability (CVE-2025-21391). Experts from the Zero Day Initiative have highlighted this bug as unprecedented in current exploits. In simple terms, this vulnerability allows an attacker to delete specific targeted files, a tactic that, when paired with a code execution flaw, could enable full system takeover. Imagine a burglar not only unlocking your door but also disabling your alarm system in one smooth stroke—that’s the potential impact of this bug on your system’s integrity.

2. Ancillary Function Driver for WinSock Vulnerability​

The update also includes a fix for an important zero-day (CVE-2025-21418) related to the Windows Ancillary Function Driver for WinSock. Rated with a CVSS score of 7.8, this bug is particularly insidious because it affects all supported Windows desktop and server systems. Although not rated as severe as some other flaws, its broad impact makes it a significant concern for every Windows environment.

3. LDAP Remote Code Execution (RCE) Vulnerability​

Another critical patch addresses a Windows Lightweight Directory Access Protocol (LDAP) vulnerability (CVE-2025-21376) that could allow remote, unauthenticated attackers to run malicious code. With a CVSS rating of 8.1, this weakness is especially dangerous due to its “wormable” nature—meaning the exploit has the potential to rapidly propagate across LDAP servers without any user interaction. The implications? A single exposed LDAP server could serve as the starting point for an extensive network compromise.

---

Beyond Windows: Excel’s Vulnerability Landscape​

Microsoft isn’t stopping at Windows itself. The update also tackles several vulnerabilities in Microsoft Excel, one of which (CVE-2025-21387) is a remote code execution flaw linked to the Preview Pane. While Microsoft states that this bug may require user interaction—like opening a malicious file or even just previewing a suspicious attachment in Outlook—the need to patch all associated vulnerabilities remains essential. With as many as six Excel-related issues addressed this month, the update underscores how even everyday productivity tools can become gateways for attackers if left unpatched.

---

Expert Insights: What Does This Mean for Windows Users?​

The details emerging from this month’s Patch Tuesday serve as a timely reminder of the critical role that regular security updates play in safeguarding systems. Let’s break down some of the broader implications:

• Elevation-of-Privilege Risks: The Windows storage bug is a textbook example of how seemingly innocuous vulnerabilities (like the ability to delete files) can be chained with more severe exploits to grant attackers undue control. This makes prompt patch deployment paramount.
• Broad Impact of Zero-days: With no user interaction required in some cases—think of the LDAP flaw—the window for exploitation is alarmingly open. For IT admins, this is a clarion call to verify that their patch management procedures are robust. Zero-day attacks exploit the period between vulnerability discovery and patch deployment, which means even a few days’ delay can have serious consequences.
• Layered Defenses for Everyday Software: The Microsoft Excel vulnerabilities may seem like a niche concern, but consider that many users frequently preview documents or attachments without a second thought. The potential for drive-by attacks in common workflows makes these updates not just beneficial but necessary.
• Real-World Implications: Enterprises that rely on Windows servers and desktops cannot afford a lapse in patching. A single exploited vulnerability can lead to service disruptions or provide a foothold for deeper network penetration, costing companies time, data, and reputation.

---

Best Practices for Administrators​

So, what should systems administrators and even individual users do in light of these updates? Here are some actionable tips:

• Test and Deploy Quickly: While it’s always wise to test patches on a small scale first, do not delay broader deployments once testing is complete. Given the active exploitation of some vulnerabilities, speed is of the essence.
• Monitor Security Advisories: Stay updated with advisory posts and technical guidance from trusted security experts. Keeping abreast of real-world exploit examples can offer early warnings for potential attacks.
• Review Patch History: Familiarize yourself with previous Patch Tuesday updates. Not only does this provide context for the emerging trend in vulnerability types, but it can also help refine your organization’s risk management strategies.

---

Final Thoughts​

Microsoft’s February 2025 Patch Tuesday might not have the sheer volume of fixes seen in January, but its focused approach on critical vulnerabilities—particularly those already exploited in the wild—makes it a must-deploy update for both enterprise networks and personal systems. For Windows users, this updated security patch is a key defense against the ever-evolving tactics of cyber attackers. As always, a little vigilance and rapid response can mean the difference between a secure system and one that’s vulnerable to attack.
Stay safe, keep your systems updated, and remember: in the world of cybersecurity, complacency is the enemy. Happy patching!

---

Source: Computer Weekly Microsoft’s February 2025 Patch Tuesday corrects 57 bugs, three critical | Computer Weekly