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KB5063709 came out on August 12, 2025. One of those updates you probably shouldn’t skip—there’s a Kerberos vulnerability in there that was getting exploited before Microsoft even had a patch ready.
Build 19045.6216 on 22H2, 19044.6216 on 21H2. The Windows Update download is about 200 MB. The Update Catalog standalone package is 700MB.
Windows 10 support ends in October 2025. KB5063709 fixes ESU enrollment so you can pay $30 for another year of patches if needed.
The Kerberos problem (CVE-2025-53779)
Here’s the deal with CVE-2025-53779. It’s an elevation of privilege bug in Windows Kerberos. Someone figures out they’re on your network with limited access; they exploit this, and suddenly they’ve got way more privileges than they should. Bad news.
What makes it worse is that attackers were already using this before August 12. Microsoft confirmed active exploitation in their security bulletin. That’s why they tagged it as zero-day. By the time most people even heard about KB5063709, someone somewhere had probably already tried hitting systems with this vulnerability.
107 other security issues got patched too, but CVE-2025-53779 is the one that matters most here. If your machine connects to any kind of network where you’re not 100% sure about every single device… yeah, install the update.
The ESU enrollment fix
Microsoft added this Extended Security Updates thing for people who aren’t ready to move to Windows 11. Pay $30 and get another year of security patches after October 2025. Sounds simple enough.
The problem was, the enrollment wizard was broken. You’d go to Windows Update settings, see the “Enroll now” link, click it, and… the window pops up for maybe half a second and closes. Gone. No error message, no explanation, just gone. Super frustrating if you were actually trying to sign up.
Turns out Microsoft had some app registration issue on their end. KB5063709 sorts that out. The wizard actually loads now. You click through, pick how you want to pay (or link your Microsoft account for the free route if you qualify), and you’re done. Finally.
One catch though—not everyone sees the enrollment option right away. Microsoft is doing a gradual rollout. Some people got it immediately after installing KB5063709; others had to wait a few days.
Other stuff they fixed
Remember that May 2025 update? Some people had their PCs randomly freeze after that one. Complete lockup; need to hold the power button to restart. Microsoft says they found a filesystem issue causing it. Should be gone now with KB5063709.
The emoji panel got broken in July’s KB5062554. You know, Win+Period to open it, search for an emoji… except search stopped working entirely. Type anything, get zero results. Every time. Microsoft fixed that too.
If you use the Changjie input method—and I know that’s a specific crowd—word selection was messed up. Fixed. Hindi Phonetic and Marathi Phonetic keyboards had issues too. Both fixed.
There’s also some Secure Boot hardening in there. SKUSiPolicy VBS Anti-rollback, if you want the technical name. Stops attackers from forcing your system to run older, vulnerable versions of system files.
Getting KB5063709 installed
Normal way: Settings, Update & Security, Windows Update, hit that Check for updates button. It should show up, download, and ask you to restart. Pretty standard stuff. If you turned on the option to get updates as soon as they’re available, it might already be installed without you doing anything.
Manual way: go to catalog.update.microsoft.com, search KB5063709, and download x64 or x86 depending on your system. Double-click the .msu file, and restart when it asks.
Manual install is useful when Windows Update is being stubborn, which… happens more often than it should.
When the install fails
Common error codes: 0x800f0922, 0x8000ffff, 0x800f0826, 0x8007000d, 0x800703fa.
The first thing to try is to reset Windows Update. Admin Command Prompt:
net stop wuauserv net stop bits
Clear the C:\Windows\SoftwareDistribution\Download folder.
net start wuauserv net start bits
Try the update again. Works for most people.
If that didn’t help, check your antivirus. I’ve seen multiple reports on TenForums and Microsoft’s own Q&A site about Norton specifically screwing up KB5063709 installation. Not just blocking it, but corrupting something in the process. People had to fully uninstall Norton (not just disable it, but actually remove it), do the update reset thing above, and then install KB5063709. After that worked, they could reinstall Norton.
Kaspersky, McAfee, and Bitdefender can cause similar issues. Disable or uninstall temporarily.
Still nothing? Could be corrupted Windows files. Open the admin command prompt again:
sfc /scannow
Let it finish. Takes a while. If SFC reports unfixable issues:
DISM /Online /Cleanup-Image /RestoreHealth
That one takes even longer and needs an internet connection. When both finish, restart and try the update.
Nuclear option if absolutely nothing works: in-place upgrade. Download the Media Creation Tool from Microsoft’s Windows 10 download page. Run it, select “Upgrade this PC now,” and keep files and apps. Reinstalls Windows and preserves your data.
About that ESU thing
Extended Security Updates: $30 for patches until October 2026. Microsoft used to reserve ESU for businesses only but opened it for consumers with Windows 10.
Three ways in:
- Link a Microsoft account and turn on settings sync. Some accounts qualify for free ESU through this—it depends on your account type and what Microsoft feels like, honestly. Worth checking.
- Microsoft Rewards points. If you’ve been collecting those, you can redeem them for ESU access.
- $30 one-time payment through Microsoft Store.
Settings > Update & Security > Windows Update > “Enroll now” link. Gradual rollout—may take several days to appear.
And just to be clear—ESU only covers security patches. No new features, no non-security bug fixes. Microsoft wants you on Windows 11. This is just a grace period for people who can’t or won’t upgrade yet.
Known problems
Microsoft lists one known issue: Noto fonts might look wrong in some apps. If you use apps that rely on Google’s Noto font family, you might see rendering weirdness. No fix yet, no workaround suggested. Microsoft says they’re looking into it.
No widespread problems reported since release.
Specs
| KB number | KB5063709 |
| Build | 19045.6216 (22H2) / 19044.6216 (21H2) |
| Released | August 12, 2025 |
| Type | Cumulative security update |
| Includes SSU | KB5063261 |
| Replaces | KB5062554, KB5062649 |
August 2025 patches for older Windows 10: KB5063877 (1809), KB5063871 (1607), KB5063889 (1507).
Verify installation
Win+R → winver → check build number (19045.6216+).
Or: Settings > Update & Security > Windows Update > View update history.
Questions people keep asking
The update keeps failing with some error code
Reset Windows Update components. Check antivirus—Norton caused issues for multiple users.
Where’s the ESU enrollment option?
Microsoft rolled it out gradually. Make sure KB5063709 is actually installed (check your build number), then give it a few days if the option isn’t showing up.
Can I just download it somewhere?
Microsoft Update Catalog. x64 for 64-bit, x86 for 32-bit. 700MB.
LTSC support
Yes—Enterprise LTSC 2021 and IoT Enterprise LTSC 2021.
Skipping the update
CVE-2025-53779 was exploited before patch release. 107 vulnerabilities patched in total.
Windows 11 upgrade
No forced upgrade. KB5063709 fixes ESU enrollment for staying on Windows 10.
Freezing after update
KB5063709 fixes the May 2025 freezing bug. New freezes—check graphics drivers, Event Viewer.
Next update
September 9, 2025.
References
