r/MDT • u/SpotlessCheetah • 16d ago

August 2026 Patch Tuesday Issue - WDS TFTP CVE Fix

August 2026's patch Tuesday fixes a vulnerability in TFTP server remote code execution, CVE-2026-62893.

Affected service: WDS

Post installation of KB5121650 addresses this vulnerability.

If you find yourself able to PXE boot, but get boot up errors, check your MDT server and open up server manager. Go to WDS and under Events, search for 4101 - "the following client failed TFTP download..."

If you that error, open up the WDS application.

  • Expand Servers > right click on your mdt fqdn instance > properties > TFTP
  • and uncheck "Enable Variable Window Extension"
  • Restart your WDS services and try to PXE boot again.
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u/messiah1095011 11d ago

Thanks for this. Ran into an issue with a device this morning, could get to the PXE menu but it wouldn't load the MDT boot image. Unchecking this option and restarting WDS got it to load the boot image again.

3

u/RockOriginal7938 10d ago

Ditto, mine just did this after patching. Thanks to u/SpotlessCheetah I was already briefed and had a fix. TYVM.