squid segfaults in AuthUserRequest when using acl external

Issue

• Since upgrading to 3.1.23-9.el6 squid segfaults in "AuthUserRequest" when using acl external.
• The same configuration worked fine with the previous version of squid (3.1.10-9.el6).
• Users can not connect to proxy,
• User receive on of the following errors: "The connection was reset" or "The proxy server is refusing".
• squid dies due to a segfault inAuthUserRequest.
• Part of squid.conf:

auth_param ntlm program /usr/bin/ntlm_auth EXAMPLE --helper-protocol=squid-2.5-ntlmssp
auth_param ntlm children 50

external_acl_type wbinfo_group_helper %LOGIN /usr/lib64/squid/wbinfo_group.pl -d
acl allowed_group external wbinfo_group_helper example-webaccess-operation

• If we change a line in squid.conf squid will work.
• From:

acl allowed_group external wbinfo_group_helper example-webaccess-operation

• To:

acl allowed_group proxy_auth REQUIRED