Guides
Evergreen explainers and how-to guides from Kernelwire: background that stays useful beyond the news cycle.
Evergreen explainers and how-to guides from Kernelwire: background that stays useful beyond the news cycle.
- CISA BOD 26-04 explained: the new KEV remediation timelines BOD 26-04 replaced BOD 22-01 on June 10, 2026. All 16 remediation timelines, forensic triage steps, KEV due dates and the December 7, 2026 deadline.
- Patch Tuesday dates for 2026 and 2027, plus other vendor patch days Next Patch Tuesday is October 13, 2026. All Patch Tuesday dates through 2027, plus SAP Patch Day, Oracle CPU and CSPU dates, Cisco bundles and Kubernetes.
- Ingress NGINX is retired: how to check your clusters and migrate Ingress NGINX was retired in March 2026 and gets no security fixes. How to find it in your clusters, pick a replacement and migrate with Ingress2Gateway.
- TLS certificate lifetimes: the 200, 100 and 47-day schedule explained Public TLS certificates are capped at 200 days since March 15, 2026, 100 days from March 2027 and 47 from 2029. Dates, validation reuse and a checklist.
- Exit code 137, 139, 143 and other container exit codes explained What container exit codes 137, 139, 143, 125-127 and 255 mean in Docker, Kubernetes and ECS, and how to confirm OOMKilled, SIGTERM or a segfault.
- SSH 'not using a post-quantum key exchange algorithm' warning explained OpenSSH 10.1+ warns when a server offers no mlkem768x25519-sha256 or sntrup761 key exchange. What it means, how to check, fix the server or mute one host.
- Windows 10 ESU year 2: cost, dates and MAK activation for businesses Windows 10 ESU year 2 costs $122 per device and runs to October 12, 2027. Dates for all three years, purchase rules and MAK activation steps.
- Cron and daylight saving time: how to avoid skipped and duplicate jobs Cron and daylight saving time: skipped and doubled jobs in cronie, systemd, Kubernetes, EventBridge and GitHub Actions, and fixes before Oct 25 and Nov 1.
- CVSS 4.0 explained: metrics, scoring and what changed from CVSS 3.1 CVSS 4.0 vs 3.1 explained: new metrics, Base/Threat/Environmental groups, CVSS-BT, score range and severity bands, with a real vector worked through.
- Kerberos RC4 deprecation: find and fix RC4 usage after CVE-2026-20833 How the Kerberos RC4 deprecation (CVE-2026-20833) works, how to find RC4 with events 4769 and KDCSVC 201-209, and how to fix accounts and keytabs.
- MITRE ATT&CK tactics list (v20): all 15 Enterprise tactics explained MITRE ATT&CK v20 tactics list: all 15 Enterprise tactics with IDs (TA0005 Stealth, TA0112 Defense Impairment), examples and what changed in v19.