Is it safe to post dxdiag on the internet?

TLDR: It's probably fine, and MS meant it not to leak anything important.

It's worth stepping through this line by line, but it's too long. So let's leave out anything that's fairly innocent.

Essentially though, an attacker must work out what your system is (and this has no obvious Personally Identifying Information), and somehow find a specific driver of OS exploits. It's probably too much work to be worth it for most.

• System Information: Mostly innocent. Machine name and exact OS version's there. If someone knew how to get to your system in the first place, and there was a specific issue with that version... maaaybe.

• DxDiag Notes: Mostly innocent

• DirectX Debug Levels: Nothing that seems to be problematic here. Mine gives no useful information.
• Display Devices, sound devices, video capture devices, DirectInput devices, System Devices: Driver versions I guess. Driver versions are useful for troubleshooting, so its needed here. If someone knew how to get to your system in the first place, and there was a specific issue with that version of the driver, maaaybe

• Disk & DVD/CD-ROM Drives: As above, and how much space you have used.

• Preferred DirectShow Filters, Media Foundation Transforms,Media Foundation Enabled Hardware Categories,Media Foundation Byte Stream Handlers, Media Foundation Scheme Handlers, Preferred Media Foundation Transforms Disabled Media Foundation Transforms Disabled Media Sources: ALL TEH CODECS. Probably completely useless to anyone.

• EVR Power Information: enhanced video renderer information. Nothing much here, I think.

• Diagnostics: what's crashed or been troublesome. Looks like this, it's handy:

  +++ WER7 +++:
  Fault bucket 120429940662, type 4
  
  Event Name: APPCRASH
  
  Response: Not available
  
  Cab Id: 0
  
  
  
  Problem signature:
  
  P1: pa.exe
  
  P2: 0.0.0.0
  
  P3: 5626c8a1
  
  P4: KERNELBASE.dll
  
  P5: 10.0.10586.162
  
  P6: 56cd45b4
  
  P7: e06d7363
  
  P8: 0000000000071f28
  
  P9: 
  
  P10:
  

On the whole? Not too likely.

This depends on how paranoid you want to be. The dxdiag.txt file generated by using the Direct X Diagnostic utility will contain a lot of information about your computer and depending on the type of user you are, one particular thing may directly identify you (if you're the kind of person to name your PC Zachiel-PC).

For example:

• NETBIOS name of your machine
• Exact build number of your operating system
• Driver versions for a variety of drivers

But in general, no, you should be OK uploading this file to the internet.