Avast 2014 causes generic IPv6 borkage on Windows 8.1

Avast Free Antivirus / Premium Security
1

With Avast 2014 (Free) and Windows 8.1 x64 RTM, IPv6 connectivity (via HE tunnel) is either not preferred (mostly) or not working at all (in browsers, happens randomly; things like ping, telnet etc. still work). Despite the default and correct settings:


C:\WINDOWS\system32>netsh interface ipv6 show prefixpolicies
Querying active state...

Precedence  Label  Prefix
----------  -----  --------------------------------
        50      0  ::1/128
        40      1  ::/0
        35      4  ::ffff:0:0/96
        30      2  2002::/16
         5      5  2001::/32
         3     13  fc00::/7
         1     11  fec0::/10
         1     12  3ffe::/16
         1      3  ::/96

Verified by

Reproduced on both physical HW installs and Hyper-V VMs. Issue immediately goes away after uninstalling Avast and reboot.

  • No such issue happens with W7 (x64).
    EDIT: - The issue does not happen on Windows 8 x64 either. (Tested on one physical box and one VM.)
2

Huh, noone seeing this?

3

I have this problem however, the reason is my ISP

Your DNS server (possibly run by your ISP) appears to have no access to the IPv6 Internet, or is not configured to use it. This may in the future restrict your ability to reach IPv6-only sites
4

I noticed this issue also and uninstalled Avast during the weekend until it is fixed.