--- a/src/libsystemd-network/dhcp6-option.c 2018-11-02 18:46:16.710217740 +0530 +++ b/src/libsystemd-network/dhcp6-option.c 2018-11-02 18:47:19.390217528 +0530 @@ -102,7 +102,7 @@ int dhcp6_option_append_ia(uint8_t **buf return -EINVAL; } - if (*buflen < len) + if (*buflen < offsetof(DHCP6Option, data) + len) return -ENOBUFS; ia_hdr = *buf;