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Microsoft Corp. today issued security updates to fix more than 80 vulnerabilities in its Windows operating systems and software. There are no known “zero-day” or actively exploited vulnerabilities in this month’s bundle from Redmond, which nevertheless includes patches for 13 flaws that earned Microsoft’s most-dire “critical” label. Meanwhile, both Apple and Google recently released updates to fix zero-day bugs in their devices.
Microsoft assigns security flaws a “critical” rating when malware or miscreants can exploit them to gain remote access to a Windows system with little or no help from users. Among the more concerning critical bugs quashed this month is CVE-2025-54918. The problem here resides with Windows NTLM, or NT LAN Manager, a suite of code for managing authentication in a Windows network environment.
Redmond rates this flaw as “Exploitation More Likely,” and although it is listed as a privilege escalation vulnerability, Kev Breen at Immersive says this one is actually exploitable over the network or the Internet.
“From Microsoft’s limited description, it appears that if an attacker is able to send specially crafted packets over the network to the target device, they would have the ability to gain SYSTEM-level privileges on the target machine,” Breen said. “The patch notes for this vulnerability state that ‘Improper authentication in Windows NTLM allows an authorized attacker to elevate privileges over a network,’ suggesting an attacker may already need to have access to the NTLM hash or the user’s credentials.”
Breen said another patch — CVE-2025-55234, a 8.8 CVSS-scored flaw affecting the Windows SMB client for sharing files across a network — also is listed as privilege escalation bug but is likewise remotely exploitable. This vulnerability was publicly disclosed prior to this month.
“Microsoft says that an attacker with network access would be able to perform a replay attack against a target host, which could result in the attacker gaining additional privileges, which could lead to code execution,” Breen noted.
CVE-2025-54916 is an “important” vulnerability in Windows NTFS — the default filesystem for all modern versions of Windows — that can lead to remote code execution. Microsoft likewise thinks we are more than likely to see exploitation of this bug soon: The last time Microsoft patched an NTFS bug was in March 2025 and it was already being exploited in the wild as a zero-day.
“While the title of the CVE says ‘Remote Code Execution,’ this exploit is not remotely exploitable over the network, but instead needs an attacker to either have the ability to run code on the host or to convince a user to run a file that would trigger the exploit,” Breen said. “This is commonly seen in social engineering attacks, where they send the user a file to open as an attachment or a link to a file to download and run.”
Critical and remote code execution bugs tend to steal all the limelight, but Tenable Senior Staff Research Engineer Satnam Narang notes that nearly half of all vulnerabilities fixed by Microsoft this month are privilege escalation flaws that require an attacker to have gained access to a target system first before attempting to elevate privileges.
“For the third time this year, Microsoft patched more elevation of privilege vulnerabilities than remote code execution flaws,” Narang observed.
On Sept. 3, Google fixed two flaws that were detected as exploited in zero-day attacks, including CVE-2025-38352, an elevation of privilege in the Android kernel, and CVE-2025-48543, also an elevation of privilege problem in the Android Runtime component.
Also, Apple recently patched its seventh zero-day (CVE-2025-43300) of this year. It was part of an exploit chain used along with a vulnerability in the WhatsApp (CVE-2025-55177) instant messenger to hack Apple devices. Amnesty International reports that the two zero-days have been used in “an advanced spyware campaign” over the past 90 days. The issue is fixed in iOS 18.6.2, iPadOS 18.6.2, iPadOS 17.7.10, macOS Sequoia 15.6.1, macOS Sonoma 14.7.8, and macOS Ventura 13.7.8.
The SANS Internet Storm Center has a clickable breakdown of each individual fix from Microsoft, indexed by severity and CVSS score. Enterprise Windows admins involved in testing patches before rolling them out should keep an eye on askwoody.com, which often has the skinny on wonky updates.
AskWoody also reminds us that we’re now just two months out from Microsoft discontinuing free security updates for Windows 10 computers. For those interested in safely extending the lifespan and usefulness of these older machines, check out last month’s Patch Tuesday coverage for a few pointers.
As ever, please don’t neglect to back up your data (if not your entire system) at regular intervals, and feel free to sound off in the comments if you experience problems installing any of these fixes.
Microsoft today unleashed updates to plug a whopping 161 security vulnerabilities in Windows and related software, including three “zero-day” weaknesses that are already under active attack. Redmond’s inaugural Patch Tuesday of 2025 bundles more fixes than the company has shipped in one go since 2017.
Rapid7‘s Adam Barnett says January marks the fourth consecutive month where Microsoft has published zero-day vulnerabilities on Patch Tuesday without evaluating any of them as critical severity at time of publication. Today also saw the publication of nine critical remote code execution (RCE) vulnerabilities.
The Microsoft flaws already seeing active attacks include CVE-2025-21333, CVE-2025-21334 and, you guessed it– CVE-2025-21335. These are sequential because all reside in Windows Hyper-V, a component that is heavily embedded in modern Windows 11 operating systems and used for security features including device guard and credential guard.
Tenable’s Satnam Narang says little is known about the in-the-wild exploitation of these flaws, apart from the fact that they are all “privilege escalation” vulnerabilities. Narang said we tend to see a lot of elevation of privilege bugs exploited in the wild as zero-days in Patch Tuesday because it’s not always initial access to a system that’s a challenge for attackers as they have various avenues in their pursuit.
“As elevation of privilege bugs, they’re being used as part of post-compromise activity, where an attacker has already accessed a target system,” he said. “It’s kind of like if an attacker is able to enter a secure building, they’re unable to access more secure parts of the facility because they have to prove that they have clearance. In this case, they’re able to trick the system into believing they should have clearance.”
Several bugs addressed today earned CVSS (threat rating) scores of 9.8 out of a possible 10, including CVE-2025-21298, a weakness in Windows that could allow attackers to run arbitrary code by getting a target to open a malicious .rtf file, documents typically opened on Office applications like Microsoft Word. Microsoft has rated this flaw “exploitation more likely.”
Ben Hopkins at Immersive Labs called attention to the CVE-2025-21311, a 9.8 “critical” bug in Windows NTLMv1 (NT LAN Manager version 1), an older Microsoft authentication protocol that is still used by many organizations.
“What makes this vulnerability so impactful is the fact that it is remotely exploitable, so attackers can reach the compromised machine(s) over the internet, and the attacker does not need significant knowledge or skills to achieve repeatable success with the same payload across any vulnerable component,” Hopkins wrote.
Kev Breen at Immersive points to an interesting flaw (CVE-2025-21210) that Microsoft fixed in its full disk encryption suite Bitlocker that the software giant has dubbed “exploitation more likely.” Specifically, this bug holds out the possibility that in some situations the hibernation image created when one closes the laptop lid on an open Windows session may not be fully encrypted and could be recovered in plain text.
“Hibernation images are used when a laptop goes to sleep and contains the contents that were stored in RAM at the moment the device powered down,” Breen noted. “This presents a significant potential impact as RAM can contain sensitive data (such as passwords, credentials and PII) that may have been in open documents or browser sessions and can all be recovered with free tools from hibernation files.”
Tenable’s Narang also highlighted a trio of vulnerabilities in Microsoft Access fixed this month and credited to Unpatched.ai, a security research effort that is aided by artificial intelligence looking for vulnerabilities in code. Tracked as CVE-2025-21186, CVE-2025-21366, and CVE-2025-21395, these are remote code execution bugs that are exploitable if an attacker convinces a target to download and run a malicious file through social engineering. Unpatched.ai was also credited with discovering a flaw in the December 2024 Patch Tuesday release (CVE-2024-49142).
“Automated vulnerability detection using AI has garnered a lot of attention recently, so it’s noteworthy to see this service being credited with finding bugs in Microsoft products,” Narang observed. “It may be the first of many in 2025.”
If you’re a Windows user who has automatic updates turned off and haven’t updated in a while, it’s probably time to play catch up. Please consider backing up important files and/or the entire hard drive before updating. And if you run into any problems installing this month’s patch batch, drop a line in the comments below, please.
Further reading on today’s patches from Microsoft:
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