ASN1 (0X80093107) Buffer Overflow Fix – Stop the Crash Now

The 30-Second Fix: Disable Automatic Root Certificate Update

I know seeing 0X80093107 mid-work is maddening – it usually hits when you're trying to open a secure connection or a signed email, and the app just crashes. The quickest fix is turning off Windows' automatic root certificate update. This stops the ASN1 parser from choking on a malformed certificate chain.

1. Press Win + R, type gpedit.msc (Windows Pro/Enterprise) or regedit (Home edition).
2. If using Group Policy Editor: go to Computer Configuration > Administrative Templates > System > Internet Communication Management > Internet Communication Settings. Enable Turn off Automatic Root Certificates Update.
3. If using Registry Editor: go to HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\SystemCertificates\AuthRoot. Create a DWORD called AutoUpdate and set it to 0.

Reboot. Test the app that was crashing. If it works, you're done. If not, move on – this is a known trigger for Office 2019 and Windows 10 build 1909, where a bad certificate bundle gets cached.

The 5-Minute Fix: Run System File Checker and DISM

If disabling auto-updates didn't help, the ASN1 buffer overflow might be tied to corrupted system files. This is common after a botched Windows update or a third-party antivirus nuking a critical DLL.

1. Open Command Prompt as Administrator: right-click Start, choose Windows Terminal (Admin) or Command Prompt (Admin).
2. Run sfc /scannow. This checks system files and replaces bad ones. Let it finish – it takes 2–5 minutes.
3. After SFC completes, run DISM /Online /Cleanup-Image /RestoreHealth. This repairs the component store that SFC relies on. It can take 10 minutes on older disks.

Reboot again. Still crashing? Time to dig into the app itself.

The 15+ Minute Fix: Identify and Reinstall the Offending Software

Error 0X80093107 often comes from a specific application using ASN1 parsing – think Outlook, Adobe Acrobat Reader DC, or a VPN client like Cisco AnyConnect. The buffer overflow happens when the software receives an ASN1 structure larger than its buffer can handle.

Step 1: Find what's throwing the error

Open Event Viewer (Win + R, type eventvwr.msc). Go to Windows Logs > Application. Look for Error events from the last hour with 0X80093107 in the details. The Source column tells you the app – like Microsoft Office, AcroRd32, or vpnagent.

Step 2: Reinstall that app

Once you know the culprit, uninstall it properly:

• Go to Settings > Apps > Installed apps. Find the app, click the three dots, choose Uninstall.
• For Office, use the Microsoft Support and Recovery Assistant (SaRA) tool – it nukes leftovers that manual uninstall misses.
• For Adobe Reader, run the Adobe Reader and Acrobat Cleaner Tool after uninstalling.

Then reinstall from the official source. Don't download from shady sites – that's how you get a corrupted installer that causes this in the first place.

Step 3: If it's a network driver or VPN

Some network drivers (Intel PROSet, Realtek) and VPN clients parse ASN1 certificates during handshakes. A driver update can resolve it. Check the manufacturer's website for a driver dated within the past 6 months. For Cisco AnyConnect specifically, version 4.10.03104 fixed a known buffer overflow in ASN1 parsing – upgrade to that or later.

Still stuck? Check the certificate store manually

If the error appears only on a specific website or email, the certificate itself might be expired or malformed. Open the certificate (double-click the padlock in your browser or email) and check the Details tab for any broken ASN1 fields like Subject Key Identifier. If you see garbage characters, contact the site admin.

This error tripped me up the first time too – I chased driver updates for an hour before realizing it was a corrupted Office certificate cache. Disabling the auto-update fixed it in 30 seconds. Try that first. You're welcome.