Latest zero-days Total: 548, in 2021: Zero-days 75, candidates: 1

SQL injection in BQE BillQuick Web Suite
CVE-2021-42258

The vulnerability allows a remote attacker to cause SQL injection, leading to remote code execution.

Privilege escalation in Microsoft Windows kernel
CVE-2021-40449

MysterySnail

A Chinese-speaking hacking group exploited a zero-day vulnerability in the Windows Win32k kernel driver to deploy a previously unknown remote access trojan (RAT).

The attacks were noticed in late August and September 2021

Privilege escalation in Apple iOS and iPadOS
CVE-2021-30883

Multiple vulnerabilities in Apache HTTP Server
CVE-2021-41773

About zero-day vulnerabilities

Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.

Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.