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Microsoft's cumulative Windows 11 update KB5121003 introduced security improvements and expanded deployment of new Secure Boot certificates, while the company said it was not aware of any known issues. After installation, however, users and game developer Embark Studios reported crashes affecting titles including ARC Raiders and The Finals, with symptoms including EXCEPTION_ACCESS_VIOLATION, Hang detected on GameThread, anti-cheat failures, black screens, refresh-rate drops, broken HDR behavior, and in some cases full system reboots.
Reports indicate the failures are tied to a compatibility conflict involving inpoutx64.sys, a third-party kernel-level port access driver used by some hardware utilities and applications. Embark published a workaround that removes the associated service and driver file, while some users said uninstalling KB5121003 restored stability, reinforcing signs of a driver-update conflict rather than a game-specific defect.
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4 events from the most recent confirmed update back to the earliest known activity.
Microsoft released cumulative update KB5121003 for Windows 11 on August 11, 2026, with security improvements, updated OS builds for 24H2 and 25H2, and related servicing changes. Microsoft also stated in the release information that it was not aware of any known issues with the update.
Embark Studios published a workaround instructing affected users to stop and delete the inpoutx64 service and remove the inpoutx64.sys driver file from the Windows drivers directory. User reports also indicated that disabling the service or uninstalling KB5121003 could stop the crashes.
Embark Studios said a new crash was introduced with Windows update KB5121003 and indicated the issue was related to changed behavior involving the third-party kernel driver inpoutx64.sys. Reports suggested the update broke compatibility with that driver on some PCs.
After installing KB5121003, users reported crashes affecting games including ARC Raiders and The Finals, along with errors such as EXCEPTION_ACCESS_VIOLATION and Hang detected on GameThread, and in some cases system reboots. Early reports also cited anti-cheat crashes, refresh-rate drops, black screens, broken HDR behavior, and similar crashes in Marvel Tōkon: Fighting Souls.
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Microsoft’s January Windows 11 cumulative update **KB5074109** has been linked to gaming performance degradation and instability on systems using **NVIDIA GeForce** GPUs, with users reporting **15–20 FPS drops**, **black screens**, and **visual artifacting** after installation. NVIDIA acknowledged the issue publicly via its GeForce forums, stating it is investigating and that uninstalling `KB5074109` appears to be the only effective temporary mitigation; some users also report that installing Microsoft’s latest optional updates may resolve the problem without removing the security update. The update is described as **security-critical** (reported as addressing **114 vulnerabilities**), creating a tradeoff between stability and exposure if the patch is removed. Separately, Microsoft has been issuing multiple **out-of-band (OOB)** fixes following January Patch Tuesday to address regressions (e.g., Remote Desktop credential prompt failures and Outlook Classic `.pst` access issues on cloud storage) and also shipped an OOB fix for an Office zero-day (**CVE-2026-21509**, a security bypass), underscoring a broader pattern of post-release remediation activity around the January patch cycle.
Jul 12, 2026
Microsoft’s January 2026 Patch Tuesday release for Windows 11 (notably **KB5074109** for 24H2/25H2) delivered roughly 100+ security fixes (including reported **zero-days**) but also introduced significant reliability regressions. Reported impacts include **system lockups**, **black screens** on systems with Nvidia/AMD GPUs, graphics-related hangs in GPU/DirectX-intensive applications, and application failures such as **Outlook Classic** freezing or failing to launch; additional issues were reported with File Explorer behavior and cloud-backed storage workflows (e.g., OneDrive/Dropbox) causing apps to become unresponsive when saving or syncing data.
Jun 29, 2026
Microsoft attributed **Windows 11 no-boot failures** seen after installing the January 2026 cumulative update `KB5074109` (Windows 11 **24H2/25H2**) to devices that had previously **failed to install the December 2025 security update** and were left in an “**improper state**” after rollback. Affected systems can crash on startup with a BSOD `UNMOUNTABLE_BOOT_VOLUME`; Microsoft said the issue appears limited to **physical devices** (no confirmed VM impact) and is working on a **partial mitigation** to prevent additional systems from entering a no-boot scenario, while continuing to investigate why some devices fail updates or end up unstable after rollback. Separately, Microsoft’s recent Windows 11 servicing and security work included **deliberately disabling legacy dial-up modem drivers** (e.g., `AGRSM64.SYS`/`AGRSM.SYS`, `SMSERL64.SYS`/`SMSERIAL.SYS`) due to reported vulnerabilities including **CVE-2023-31096** (EoP) and **CVE-2025-24052** (stack-based buffer overflow), which can present risk even if the modem hardware is unused—at the cost of breaking connectivity for niche systems relying on those drivers. Microsoft also patched **nine bypasses** reported by Google Project Zero that could undermine the new **Windows Administrator Protection** feature by enabling silent admin privilege gains via legacy Windows/UAC behaviors (including a token/Logon Sessions-related technique involving `NtQueryInformationToken` and DOS device object directory creation), ahead of broader availability beyond Insider builds.
Jun 29, 2026