A 0-Day is a software vulnerability without an available fix, creating risk because defenders have limited time to mitigate exploitation.
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Background for this topic.
0-Day describes a software vulnerability unknown to the software maker or unpatched when first exploited. Attackers can use these flaws immediately, as no official fix or signature exists to block the exploit. Such vulnerabilities often affect widely deployed software or hardware, making them valuable for targeted attacks or widespread campaigns.
Because defenders lack patches or reliable detection signatures initially, they must rely on anomaly detection, network monitoring, and threat intelligence to identify suspicious activity linked to 0-day exploits. Rapid patching once a fix is released is critical to reduce exposure. Tracking emerging 0-day threats helps prioritize defensive measures and informs risk management decisions in environments where unpatched vulnerabilities pose significant security risks.
A researcher known as "Chaotic Eclipse" has published a proof-of-concept exploit for a second Microsoft Defender zero-day, dubbed "RedSun," in the past two weeks, protesting how the company works with cybersecurity researchers. [...]
You know that feeling when you open your feed on a Thursday morning and it's just... a lot? Yeah. This week delivered. We've got hackers getting creative in ways that are almost impressive if you ignore the whole "crime" part, ancient vulnerabilities somehow still ruining people's days, and enough supply chain drama to fill a season of television nobody asked for
Microsoft has patched two zero-day flaws and over 160 others
Microsoft on Tuesday released updates to address a record 169 security flaws across its product portfolio, including one vulnerability that has been actively exploited in the wild
Microsoft today pushed software updates to fix a staggering 167 security vulnerabilities in its Windows operating systems and related software, including a SharePoint Server zero-day and a publicly disclosed weakness in Windows Defender dubbed "BlueHammer." Separately, Google Chrome fixed its fourth zero-day of 2026, and an emergency update for Adobe Reader nixes an actively exploited flaw that can lead to remote code execution.
The vendor disclosed one actively exploited zero-day vulnerability in Microsoft Office SharePoint that allows attackers to view information and make changes to disclosed information. The post Microsoft drops its second-largest monthly batch of defects on record appeared first on CyberScoop.
Today is Microsoft's April 2026 Patch Tuesday with security updates for 167 flaws, including 2 zero-day vulnerabilities. [...]
April 2026 Patch Tuesday is the largest in years: 167 CVEs from Microsoft plus 344 released throughout the month for 512 total updates. An actively exploited SharePoint zero-day, wormable RCEs in Remote Desktop and Active Directory, and preview-pane Office exploits demand immediate action.
An attacker has been using maliciously crafted PDF files to exploit a zero-day in Adobe Acrobat and Reader for at least four months.
Adobe has released an emergency security update for Acrobat Reader to fix a vulnerability, tracked as CVE-2026-34621, that has been exploited in zero-day attacks since at least December. [...]
Monday is back, and the weekend’s backlog of chaos is officially hitting the fan. We are tracking a critical zero-day that has been quietly living in your PDFs for months, plus some aggressive state-sponsored meddling in infrastructure that is finally coming to light. It is one of those mornings where the gap between a quiet shift and a full-blown incident response is basically
Anthropic restricted its Mythos Preview model last week after it autonomously found and exploited zero-day vulnerabilities in every major operating system and browser. Palo Alto Networks' Wendi Whitmore warned that similar capabilities are weeks or months from proliferation. CrowdStrike's 2026 Global Threat Report puts average eCrime breakout time at 29 minutes. Mandiant's M-Trends
Or it's a bunch of pre-IPO hype. Either way, we're giving it the once-over on this week's episode Kettle Anthropic dropped a doozy on us this week with the launch of Mythos, an AI model it says is able to find and exploit zero-day vulnerabilities with a shocking level of ability. …