Microsoft in the present day unleashed updates to plug a whopping 161 safety vulnerabilities in Home windows and associated software program, together with three “zero-day” weaknesses which can be already below energetic assault. Redmond’s inaugural Patch Tuesday of 2025 bundles extra fixes than the corporate has shipped in a single go since 2017.
Rapid7‘s Adam Barnett says January marks the fourth consecutive month the place Microsoft has revealed zero-day vulnerabilities on Patch Tuesday with out evaluating any of them as crucial severity at time of publication. Immediately additionally noticed the publication of 9 crucial distant code execution (RCE) vulnerabilities.
The Microsoft flaws already seeing energetic assaults embody CVE-2025-21333, CVE-2025-21334 and, you guessed it– CVE-2025-21335. These are sequential as a result of all reside in Home windows Hyper-V, a element that’s closely embedded in trendy Home windows 11 working methods and used for safety features together with gadget guard and credential guard.
Tenable’s Satnam Narang says little is understood concerning the in-the-wild exploitation of those flaws, aside from the truth that they’re all “privilege escalation” vulnerabilities. Narang stated we are inclined to see quite a lot of elevation of privilege bugs exploited within the wild as zero-days in Patch Tuesday as a result of it’s not at all times preliminary entry to a system that’s a problem for attackers as they’ve numerous avenues of their pursuit.
“As elevation of privilege bugs, they’re getting used as a part of post-compromise exercise, the place an attacker has already accessed a goal system,” he stated. “It’s sort of like if an attacker is ready to enter a safe constructing, they’re unable to entry safer components of the ability as a result of they need to show that they’ve clearance. On this case, they’re in a position to trick the system into believing they need to have clearance.”
A number of bugs addressed in the present day earned CVSS (risk score) scores of 9.8 out of a doable 10, together with CVE-2025-21298, a weak point in Home windows that would permit attackers to run arbitrary code by getting a goal to open a malicious .rtf file, paperwork sometimes opened on Workplace functions like Microsoft Phrase. Microsoft has rated this flaw “exploitation extra possible.”
Ben Hopkins at Immersive Labs referred to as consideration to the CVE-2025-21311, a 9.8 “crucial” bug in Home windows NTLMv1 (NT LAN Supervisor model 1), an older Microsoft authentication protocol that’s nonetheless utilized by many organizations.
“What makes this vulnerability so impactful is the truth that it’s remotely exploitable, so attackers can attain the compromised machine(s) over the web, and the attacker doesn’t want vital information or abilities to realize repeatable success with the identical payload throughout any susceptible element,” Hopkins wrote.
Kev Breen at Immersive factors to an attention-grabbing flaw (CVE-2025-21210) that Microsoft mounted in its full disk encryption suite Bitlocker that the software program large has dubbed “exploitation extra possible.” Particularly, this bug holds out the likelihood that in some conditions the hibernation picture created when one closes the laptop computer lid on an open Home windows session will not be totally encrypted and might be recovered in plain textual content.
“Hibernation photographs are used when a laptop computer goes to sleep and incorporates the contents that have been saved in RAM for the time being the gadget powered down,” Breen famous. “This presents a major potential impression as RAM can include delicate information (corresponding to passwords, credentials and PII) that will have been in open paperwork or browser classes and might all be recovered with free instruments from hibernation information.”
Tenable’s Narang additionally highlighted a trio of vulnerabilities in Microsoft Entry mounted this month and credited to Unpatched.ai, a safety analysis effort that’s aided by synthetic intelligence on the lookout for vulnerabilities in code. Tracked as CVE-2025-21186, CVE-2025-21366, and CVE-2025-21395, these are distant code execution bugs which can be exploitable if an attacker convinces a goal to obtain and run a malicious file by social engineering. Unpatched.ai was additionally credited with discovering a flaw within the December 2024 Patch Tuesday launch (CVE-2024-49142).
“Automated vulnerability detection utilizing AI has garnered quite a lot of consideration just lately, so it’s noteworthy to see this service being credited with discovering bugs in Microsoft merchandise,” Narang noticed. “It might be the primary of many in 2025.”
For those who’re a Home windows person who has automated updates turned off and haven’t up to date shortly, it’s in all probability time to play catch up. Please think about backing up necessary information and/or your complete laborious drive earlier than updating. And in the event you run into any issues putting in this month’s patch batch, drop a line within the feedback under, please.
Additional studying on in the present day’s patches from Microsoft:
