I think the big question on everyone’s mind this month will be what happened at Microsoft? The updates were released 40-minutes later than usual. This is not a big deal, we wouldn’t even notice a delay that small from most organizations, but Microsoft isn’t most organizations, and their own punctuality made this delay obvious. Once the patches were released, they contained an FAQ note that Windows 10 security updates were not currently available and would be released as soon as possible with a revision to the CVE to notify customers. This really makes you wonder what went wrong with the Windows 10 updates that they are not presently available.
As an organization, you need to wonder how long updates will be delayed. Are we talking hours or days? These vulnerabilities have now been announced, malicious actors will be reverse engineering the updates to identify the vulnerabilities and how to exploit them, and Windows 10 users are left without the ability to update. If I was responsible for risk in my organization, I’d probably be a little concerned about this delay. In other words, if I were a CISO, I’d be paying attention to how long this delay persists and how impacted my organization is.
There is only one Exploitation Detected (aka 0-day vulnerability) in today’s drop and that is CVE-2025-29824, a vulnerability in the Windows Common Log File System (CLFS) Driver. Now that a patch is available, updating this should be considered a priority for security teams. I was recently discussing CLFS vulnerabilities and how they seem to come in waves. When a vulnerability in CLFS is patched, people tend to dig around and look at what’s going on and come across other vulnerabilities in the process. If I was a gambler, I would bet on CLFS appearing again next month.
This is a month that really demonstrates that CVSS severity is not necessarily the best metric for prioritization. CVE-2025-29824, our 0-day, has a base score of 7.8, while another vulnerability that I would pay attention to, CVE-2025-27472, only has a base score of 5.4. In the case of Microsoft, prioritization is better done utilizing the Microsoft Exploitability Index and focusing on vulnerabilities with an index of 0 (Exploitation Detected) or 1 (Exploitation More Likely).
So, why did a vulnerability with a relatively low CVSS base score stand out to me? CVE-2025-27472 describes a vulnerability in Mark of the Web (MOTW) that allows for the potential bypass of SmartScreen. Microsoft has listed this vulnerability has Exploitation More Likely and it is common to see MOTW vulnerabilities utilized by threat actors. I wouldn’t be surprised if this is a vulnerability that we see exploited in the future.
If I were an infosec buyer, think CISO, I’d be looking at the trends in Microsoft vulnerabilities – recurring and commonly exploited technologies like Office, Edge, CLFS, and MOTW – and I’d be asking my vendors how they are helping me proactively defend against these types of vulnerabilities. There are definitely themes that we see pop up again and again, themes that I would hope vendors are thinking about either to proactively prevent, accurately detect, or properly prioritize.
I recently mentioned to someone that I feel a lot of the time there’s a bit of a hunch or a gut feeling involved in determining whether something is critical or not because there aren’t a lot of truly useful global systems for prioritizing vulnerabilities. When I review a list of vulns like the bundle that dropped today, I do get a gut feeling about some of them and I try to listen to that feeling. While it may not be the most accurate metric, it’s an important bit of intuition to develop and a critical skill for any CISO to have.
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