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Patch Tuesday, October 2025 ‘End of 10’ Edition

14 October 2025 at 18:57

Microsoft today released software updates to plug a whopping 172 security holes in its Windows operating systems, including at least two vulnerabilities that are already being actively exploited. October’s Patch Tuesday also marks the final month that Microsoft will ship security updates for Windows 10 systems. If you’re running a Windows 10 PC and you’re unable or unwilling to migrate to Windows 11, read on for other options.

The first zero-day bug addressed this month (CVE-2025-24990) involves a third-party modem driver called Agere Modem that’s been bundled with Windows for the past two decades. Microsoft responded to active attacks on this flaw by completely removing the vulnerable driver from Windows.

The other zero-day is CVE-2025-59230, an elevation of privilege vulnerability in Windows Remote Access Connection Manager (also known as RasMan), a service used to manage remote network connections through virtual private networks (VPNs) and dial-up networks.

“While RasMan is a frequent flyer on Patch Tuesday, appearing more than 20 times since January 2022, this is the first time we’ve seen it exploited in the wild as a zero day,” said Satnam Narang, senior staff research engineer at Tenable.

Narang notes that Microsoft Office users should also take note of CVE-2025-59227 and CVE-2025-59234, a pair of remote code execution bugs that take advantage of “Preview Pane,” meaning that the target doesn’t even need to open the file for exploitation to occur. To execute these flaws, an attacker would social engineer a target into previewing an email with a malicious Microsoft Office document.

Speaking of Office, Microsoft quietly announced this week that Microsoft Word will now automatically save documents to OneDrive, Microsoft’s cloud platform. Users who are uncomfortable saving all of their documents to Microsoft’s cloud can change this in Word’s settings; ZDNet has a useful how-to on disabling this feature.

Kev Breen, senior director of threat research at Immersive, called attention to CVE-2025-59287, a critical remote code execution bug in the Windows Server Update Service  (WSUS) — the very same Windows service responsible for downloading security patches for Windows Server versions. Microsoft says there are no signs this weakness is being exploited yet. But with a threat score of 9.8 out of possible 10 and marked “exploitation more likely,” CVE-2025-59287 can be exploited without authentication and is an easy “patch now” candidate.

“Microsoft provides limited information, stating that an unauthenticated attacker with network access can send untrusted data to the WSUS server, resulting in deserialization and code execution,” Breen wrote. “As WSUS is a trusted Windows service that is designed to update privileged files across the file system, an attacker would have free rein over the operating system and could potentially bypass some EDR detections that ignore or exclude the WSUS service.”

For more on other fixes from Redmond today, check out the SANS Internet Storm Center monthly roundup, which indexes all of the updates by severity and urgency.

Windows 10 isn’t the only Microsoft OS that is reaching end-of-life today; Exchange Server 2016, Exchange Server 2019, Skype for Business 2016, Windows 11 IoT Enterprise Version 22H2, and Outlook 2016 are some of the other products that Microsoft is sunsetting today.

If you’re running any Windows 10 systems, you’ve probably already determined whether your PC meets the technical hardware specs recommended for the Windows 11 OS. If you’re reluctant or unable to migrate a Windows 10 system to Windows 11, there are alternatives to simply continuing to use Windows 10 without ongoing security updates.

One option is to pay for another year’s worth of security updates through Microsoft’s Extended Security Updates (ESU) program. The cost is just $30 if you don’t have a Microsoft account, and apparently free if you register the PC to a Microsoft account. This video breakdown from Ask Your Computer Guy does a good job of walking Windows 10 users through this process. Microsoft emphasizes that ESU enrollment does not provide other types of fixes, feature improvements or product enhancements. It also does not come with technical support.

If your Windows 10 system is associated with a Microsoft account and signed in when you visit Windows Update, you should see an option to enroll in extended updates. Image: https://www.youtube.com/watch?v=SZH7MlvOoPM

Windows 10 users also have the option of installing some flavor of Linux instead. Anyone seriously considering this option should check out the website endof10.org, which includes a plethora of tips and a DIY installation guide.

Linux Mint is a great option for Linux newbies. Like most modern Linux versions, Mint will run on anything with a 64-bit CPU that has at least 2GB of memory, although 4GB is recommended. In other words, it will run on almost any computer produced in the last decade.

Linux Mint also is likely to be the most intuitive interface for regular Windows users, and it is largely configurable without any fuss at the text-only command-line prompt. Mint and other flavors of Linux come with LibreOffice, which is an open source suite of tools that includes applications similar to Microsoft Office, and it can open, edit and save documents as Microsoft Office files.

If you’d prefer to give Linux a test drive before installing it on a Windows PC, you can always just download it to a removable USB drive. From there, reboot the computer (with the removable drive plugged in) and select the option at startup to run the operating system from the external USB drive. If you don’t see an option for that after restarting, try restarting again and hitting the F8 button, which should open a list of bootable drives. Here’s a fairly thorough tutorial that walks through exactly how to do all this.

And if this is your first time trying out Linux, relax and have fun: The nice thing about a “live” version of Linux (as it’s called when the operating system is run from a removable drive such as a CD or a USB stick) is that none of your changes persist after a reboot. Even if you somehow manage to break something, a restart will return the system back to its original state.

As ever, if you experience any difficulties during or after applying this month’s batch of patches, please leave a note about it in the comments below.

Microsoft Issues Emergency Patch for Critical WSUS Remote Code Execution Flaw (CVE-2025-59287)

CVE-2025-59287

Microsoft has released an urgent out-of-band security update to address a severe remote code execution (RCE) vulnerability in Windows Server Update Services (WSUS). The flaw, tracked as CVE-2025-59287, poses a direct risk to organizations that utilize WSUS to manage Windows updates across their IT infrastructure. 

Overview of the CVE-2025-59287 Vulnerability 

The vulnerability, identified as a case of CWE-502: Deserialization of Untrusted Data, occurs when WSUS improperly deserializes untrusted objects. A remote, unauthenticated attacker could exploit this flaw by sending a specially crafted request to the WSUS service.  Because WSUS commonly runs under the SYSTEM account, successful exploitation would allow the attacker to execute arbitrary code with the highest privileges, effectively gaining full control of the targeted system.  Microsoft has rated the flaw as Critical with a CVSS 3.1 base score of 9.8. The attack vector is network-based, requires no authentication or user interaction, and has low complexity. The vulnerability’s scope, confidentiality, integrity, and availability impacts are all classified as high. Microsoft has also assessed exploitation as “More Likely,” increasing the urgency for administrators to patch affected systems immediately. 

Affected Versions 

The RCE vulnerability affects several supported editions of Windows Server, including: 
  • Windows Server 2012 and 2012 R2 
  • Windows Server 2016 
  • Windows Server 2019 
  • Windows Server 2022 (including the 23H2 Server Core edition) 
  • Windows Server 2025 
By default, the WSUS server role is not enabled on Windows Server installations. However, once enabled, unpatched servers become vulnerable to exploitation. Microsoft emphasizes that servers without the WSUS role activated are not affected by CVE-2025-59287. 

Timeline of Discovery and Patching 

The vulnerability was first disclosed on October 14, 2025, with Microsoft formally registering it under the identifier CVE-2025-59287. Following the discovery, Microsoft released an out-of-band update on October 23, 2025, after confirming the existence of publicly available proof-of-concept (PoC) exploit code. This prompted an update to the CVSS temporal score to reflect the increased maturity of the exploit.  The update is available through multiple channels, including Windows Update, Microsoft Update, and Microsoft Update Catalog. Systems configured to automatically receive updates will download and install the patch without manual intervention. A system reboot is required after applying the update. 

Mitigation and Workarounds

For organizations unable to immediately install the October 23, 2025, patch, Microsoft has provided several temporary mitigations: 
  • Disable the WSUS Server Role: Doing so prevents exploitation but also halts update delivery to clients. 
  • Block Inbound Traffic: Administrators can block ports 8530 and 8531 on the host firewall to render WSUS non-operational and mitigate the risk of attack. 
Microsoft warns that these workarounds should remain in place until the official patch is successfully applied. Reverting them before updating could leave systems exposed to potential exploitation. 

Exploitability and Risk 

At the time of release, Microsoft reported no evidence of active exploitation or public disclosure beyond the proof-of-concept code. However, a successful compromise of a WSUS server could allow attackers to distribute malicious updates throughout an organization’s network, manipulate system configurations, or pivot deeper into internal environments.  CVE-2025-59287 was reported by Markus Wulftange of CODE WHITE GmbH, with Microsoft acknowledging his contribution to identifying and responsibly disclosing the issue.  The ability for an unauthenticated attacker to achieve RCE over a network, without user interaction, elevates this vulnerability to a critical priority. Organizations relying on WSUS should verify that the October 23, 2025, update has been applied across all affected systems. Until fully patched, any unprotected WSUS installation remains at risk of compromise.  
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