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.
During the second day of Pwn2Own Berlin 2025, competitors earned $435,000 after exploiting zero-day bugs in multiple products, including Microsoft SharePoint, VMware ESXi, Oracle VirtualBox, Red Hat Enterprise Linux, and Mozilla Firefox. [...]
Even after their zero-day vulnerability turned into an n-day, attackers known as Marbled Dust or Sea Turtle continued to spy on military targets that had failed to patch Output Messenger.
Hackers are running a worldwide cyberespionage campaign dubbed 'RoundPress,' leveraging zero-day and n-day flaws in webmail servers to steal email from high-value government organizations. [...]
On the first day of Pwn2Own Berlin 2025, security researchers were awarded $260,000 after successfully demonstrating zero-day exploits for Windows 11, Red Hat Linux, Docker Desktop, and Oracle VirtualBox. [...]
A Russia-linked threat actor has been attributed to a cyber espionage operation targeting webmail servers such as Roundcube, Horde, MDaemon, and Zimbra via cross-site scripting (XSS) vulnerabilities, including a then-zero-day in MDaemon, according to new findings from ESET
The security software maker said the vulnerabilities in Endpoint Manager Mobile have been exploited in the wild against "a very limited number of customers" — for now — and stem from open source libraries.
New phishing tactics are abusing trusted domains, real CAPTCHAs, and server-side email validation to selectively target victims with customized fake login pages. Keep Aware's latest research breaks down the full attack chain and how these zero-day phish operate. [...]
Microsoft on Tuesday released software updates to fix at least 70 vulnerabilities in Windows and related products, including five zero-day flaws that are already seeing active exploitation. Adding to the sense of urgency with this month's patch batch from Redmond are fixes for two other weaknesses that now have public proof-of-concept exploits available.
Microsoft has patched seven zero-day bugs, five of which were exploited in the wild
Fortinet has patched a critical security flaw that it said has been exploited as a zero-day in attacks targeting FortiVoice enterprise phone systems
Microsoft Researchers Link Turkish Spy Group to Output Messenger Zero-Day HackA Turkish-linked cyberespionage group known as Marbled Dust exploited a zero-day in the Output Messenger Server Manager application to spy on Kurdish military operations in Iraq. Microsoft reported the hack and called for immediate mitigation to block credential theft and malware delivery.
Microsoft's May 2025 Patch Tuesday update also contains four other actively exploited zero-day security vulnerabilities, two publicly known bugs, and 12 critical patches.
SAP has released patches to address a second vulnerability exploited in recent attacks targeting SAP NetWeaver servers as a zero-day. [...]
Today is Microsoft's May 2025 Patch Tuesday, which includes security updates for 72 flaws, including five actively exploited and two publicly disclosed zero-day vulnerabilities. [...]
Fortinet released security updates to patch a critical remote code execution vulnerability exploited as a zero-day in attacks targeting FortiVoice enterprise phone systems. [...]
Marbled Dust has been exploiting a vulnerability in user accounts associated with the Kurdish military operating in Iraq for over a year, according to Microsoft
'MarbledDust' gang has honed the skills it uses to assist Ankara Turkish spies exploited a zero-day bug in a messaging app to collect info on the Kurdish army in Iraq, according to Microsoft, which says the attacks began more than a year ago.…
A Türkiye-affiliated threat actor exploited a zero-day security flaw in an Indian enterprise communication platform called Output Messenger as part of a cyber espionage attack campaign since April 2024
A Türkiye-backed cyberespionage group exploited a zero-day vulnerability to attack Output Messenger users linked to the Kurdish military in Iraq. [...]
Agentic-native startups threaten to reduce the zero-day problem to just a zero-hour issue. Of course, AI agents will accelerate offensive attacks as well.