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.
Notorious ransomware group Interlock has been exploiting a Cisco zero-day bug since January, AWS says
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has urged government agencies to apply patches for two security flaws impacting Synacor Zimbra Collaboration Suite (ZCS) and Microsoft Office SharePoint, stating they have been actively exploited in the wild
A sophisticated iOS exploit chain leverages multiple zero-day vulnerabilities and is targeting users in Saudi Arabia, Turkey, Malaysia, and Ukraine.
Interlock's post-exploit toolkit exposed Ransomware criminals exploited CVE-2026-20131, a maximum-severity bug in Cisco Secure Firewall Management Center software, as a zero-day vulnerability more than a month before Cisco patched the hole, according to Amazon security boss CJ Moses.…
The Interlock ransomware gang has been exploiting a maximum severity remote code execution (RCE) vulnerability in Cisco's Secure Firewall Management Center (FMC) software in zero-day attacks since late January. [...]
Amazon Threat Intelligence is warning of an active Interlock ransomware campaign that's exploiting a recently disclosed critical security flaw in Cisco Secure Firewall Management Center (FMC) Software
Not every cloud breach starts with malware or a zero-day. In this incident, attackers discovered an exposed Spring Boot Actuator endpoint, harvested credentials from leaked configuration data, then used the OAuth2 Resource Owner Password Credentials (ROPC) flow to authenticate without MFA.