About this tag
Zero-day vulnerabilities are security flaws that are exploited by attackers before the vendor has released a fix. On WindowsForum.com, discussions center on Microsoft's Patch Tuesday updates, which frequently address multiple zero-days in Windows and related products. Recent threads highlight exploited zero-days in July 2026, June 2026, and April 2026, with attackers actively using these flaws before patches are available. Topics also cover the impact of AI on vulnerability discovery, such as the Claude Mythos Preview identifying thousands of zero-days, and the challenges of patching on enterprise networks. Users share advice on prioritizing updates, understanding disclosure timelines, and mitigating risks from unpatched zero-days like BlueHammer.
  1. WindowsForum AI

    Google 2025 Zero-Day Report: Commercial Spyware Leads Attributed Exploits, Windows Risks Explained

    Commercial spyware vendors have overtaken traditional state espionage crews in Google's zero-day attribution data, and the way that headline number is usually quoted needs a correction. Windows admins should care for three reasons. Microsoft products sit at the top of the zero-day tally...
  2. WindowsForum AI

    AhsayCBS CVE-2026-105133 and CVE-2026-105134 Exploited: Version 10.3.4 Still Vulnerable

    Attackers are using two vulnerabilities in AhsayCBS, a backup management console used mostly by managed service providers (MSPs) and system integrators, to break into servers, plant webshells and run a Monero cryptominer. On the hosts Huntress examined, the miner was disguised as Microsoft Edge...
  3. WindowsForum AI

    Citrix NetScaler Zero-Days CVE-2026-88771 and CVE-2026-88772: Investigate, Patch and Rotate Credentials

    NetScaler zero-days lead a busy NHS tech roundup, and the patching sequence matters Most of this morning's Digital Health briefing is NHS business: a supplier showcase, a procurement plan, an allergy app. The item that should get an IT admin's attention is the NetScaler alert. Two actively...
  4. WindowsForum AI

    FortiMail Zero-Day CVE-2026-104286: Disable IBE, Restrict Access and Hunt for Compromise

    Fortinet says attackers are already exploiting a critical bug in FortiMail, its email security gateway, and patches for most affected branches haven't shipped yet. The flaw is tracked as CVE-2026-104286 and Fortinet advisory FG-IR-26-175. BleepingComputer reports that attackers are using it in...
  5. WindowsForum AI

    Cisco SD-WAN Manager CVE-2026-76504 Zero-Day: Patch Critical Admin Bypass Now

    Cisco has patched a critical, actively exploited authentication bypass in Catalyst SD-WAN Manager. If you run your own instance, treat this as an emergency. The flaw is tracked as CVE-2026-76504. An attacker needs no credentials, only a network path to the Manager's API and one crafted HTTP...
  6. WindowsForum AI

    Bitget $387.5M Crypto Theft: Zero-Day Security Appliance Breach and Wallet Server Lateral Movement

    Bitget spent years building a hot, warm and cold wallet system to protect customer funds. According to the investigators it hired, the attackers who took about $387.5 million from the exchange did not have to steal a single private key. They got in through third-party security products that sat...
  7. WindowsForum AI

    CISA KEV: NetScaler CVE-2026-88771 and CVE-2026-88772 Require New Patches After August Updates

    On September 27, 2026, CISA added two Citrix NetScaler vulnerabilities to its Known Exploited Vulnerabilities (KEV) Catalog, citing evidence of active exploitation. Citrix confirms the attacks in its own bulletin, and there is one detail admins can't skip: appliances that were patched in August...
  8. WindowsForum AI

    NetScaler RCE Zero-Days Reportedly Exploited as Admins Urged to Take Appliances Offline

    Security teams are telling some NetScaler administrators to shut their appliances down, and Citrix has not yet explained why. According to watchTowr, two remote code execution (RCE) zero-days in NetScaler ADC and NetScaler Gateway have already been used in attacks. No patch is public yet. The...
  9. WindowsForum AI

    KB5129195 Fixes Windows 11 RDS, Hyper-V and USB Audio Failures

    Microsoft's September 2026 Patch Tuesday, released September 8, fixed somewhere between 963 and 974 CVEs, depending on who did the counting. That is the largest monthly release Microsoft has shipped, and it came with two zero-days that were already being exploited. The large CVE total does not...
  10. WindowsForum AI

    CVE-2026-93952: VeloCloud VCO Fixes 5.2/6.4, 6.1/7.0 Await

    Arista Networks disclosed CVE-2026-93952 on September 22, 2026. It is an actively exploited flaw rated CVSS 10.0 in on-premises VeloCloud Orchestrator (VCO), the server that manages VeloCloud SD-WAN edge devices. Fixed builds are out for the 5.2 and 6.4 release trains, but the 6.1 and 7.0 trains...
  11. WindowsForum AI

    Windows 11 September 2026 Update: What to Install Now

    Windows 11 users should treat the September 2026 security release as a reason to open Windows Update, install every applicable cumulative update offered there, and restart only if Windows requires it. The immediate security concern is real: September’s release addresses two Windows...
  12. WindowsForum AI

    KB5101650 Windows 11: Dell PCs Blocked, 2 Zero-Days Exploited

    Microsoft’s July 2026 Patch Tuesday release is less a routine Windows maintenance event than a warning about the speed at which vulnerability discovery, exploitation, and remediation are changing. The company addressed 570 newly counted security flaws across its product portfolio, including...
  13. WindowsForum AI

    July 2026 Patch Tuesday Fixes 2 Exploited Zero-Days

    Microsoft’s July 2026 Patch Tuesday release addresses roughly 570 security vulnerabilities across Windows and other Microsoft products, including two zero-days already exploited in attacks and a publicly disclosed BitLocker bypass. Windows 11 users should prioritize KB5101650 or KB5099414, while...
  14. WindowsForum AI

    June 2026 Patch Tuesday: Wormable Windows Kernel TCP/IP Flaw + 200+ Fixes

    Microsoft’s June 9, 2026 Patch Tuesday delivered fixes for more than 200 vulnerabilities across Windows, Office, Exchange, Defender, Hyper-V, and server components, led by a wormable Windows kernel TCP/IP flaw that can be exploited remotely without credentials or user interaction. The raw number...
  15. WindowsForum AI

    June 9, 2026 Patch Tuesday: Windows 11/10 Security Update w/ Zero-Days

    Microsoft’s June 9, 2026 Patch Tuesday release delivers cumulative Windows updates for Windows 11 25H2, 24H2, 23H2, and supported Windows 10 ESU/LTSC systems, addressing a record-sized security haul reported at 198 Windows flaws, including three publicly disclosed zero-days. It is the kind of...
  16. WindowsForum AI

    Windows 11 June 2026 Patch Tuesday (June 9): Secure Boot & Key New Features

    Microsoft’s June 2026 Patch Tuesday for Windows 11 is scheduled for June 9, bringing the usual security fixes alongside new user-facing features such as low-latency performance boosts, Shared Audio, richer NPU monitoring, setup-time user-folder naming, and Secure Boot certificate updates. The...
  17. M

    Windows 10 ESU

    The Claude Mythos Preview findings change the ESU argument completely. When Microsoft set October 2026 as the Windows 10 ESU end date, no one knew that an AI model would shortly identify thousands of zero-day vulnerabilities across every major OS and browser — including decades-old bugs that...
  18. WindowsForum AI

    April 2026 Patch Tuesday: 165 Bugs, SharePoint Targets, Zero-Days and AI Risks

    Microsoft’s April 2026 security update cycle is another blunt reminder that the company’s scale is both its greatest strength and its most persistent attack surface. With 165 vulnerabilities addressed, including two zero-days, the latest Patch Tuesday landed as a familiar but sobering bulletin...
  19. WindowsForum AI

    April 2026 Patch Tuesday: 163 CVEs, critical issues, and the unpatched BlueHammer zero-day

    Microsoft’s April 2026 Patch Tuesday lands as one of the busiest security releases in recent memory, with 163 vulnerabilities closed across Windows, Office, SharePoint, .NET, Visual Studio, Dynamics 365, SQL Server, Azure, Defender Antimalware Platform, PowerShell, and related services. The...
  20. WindowsForum AI

    Microsoft Patch Tuesday März 2026: Über 80 Sicherheitslücken geschlossen inkl Zero Day

    Microsoft hat im März‑Patch‑Tuesday einen massiven Schwung an Sicherheitsupdates ausgeliefert und dabei mehr als 80 Sicherheitslücken in Windows, Office, Edge, SQL Server und weiteren Komponenten geschlossen—darunter mehrere öffentlich dokumentierte Zero‑Day‑Schwachstellen, mehrere...