The spnego_gss_accept_sec_context function in lib/gssapi/spnego/spnego_mech.c in the SPNEGO GSS-API functionality in MIT Kerberos 5 (aka krb5) 1.7 before 1.7.2 and 1.8 before 1.8.1 allows remote attackers to cause a denial of service (assertion failure and daemon crash) via an invalid packet that triggers incorrect preparation of an error token.