--- a/src/lib/gssapi/krb5/accept_sec_context.c
+++ b/src/lib/gssapi/krb5/accept_sec_context.c
@@ -561,6 +561,13 @@ kg_accept_krb5(minor_status, context_handle,
}
#endif
+ if (authdat->checksum == NULL) {
+ /* missing checksum counts as "inappropriate type" */
+ code = KRB5KRB_AP_ERR_INAPP_CKSUM;
+ major_status = GSS_S_FAILURE;
+ goto fail;
+ }
+
if (authdat->checksum->checksum_type != CKSUMTYPE_KG_CB) {
/* Samba does not send 0x8003 GSS-API checksums */
krb5_boolean valid;