While the Pali scriptures address (or at least reference) a number of specific sufferings that a human being can be subject to (Jealousy, Anger, Fear, etc.), do any of the teachings deal with the specific suffering of Insecurity (and how to overcome it)? Meaning a lack of self-confidence, usually caused by the mind making itself subject to fears and illusions that creep in and which it lacks the strength to banish or prevent in the first place.
1.One of the ways to deal with anxiety,insecurity or lack of self confidence is by developing Sila (Morality,Integrity,Virtue,Ethics).
"Five blessings, householders, accrue to the righteous person through his practice of virtue: great increase of wealth through his diligence; a favorable reputation; a confident deportment, without timidity, in every society, be it that of nobles, brahmans, householders, or ascetics; a serene death; and, at the breaking up of the body after death, rebirth in a happy state, in a heavenly world." — DN 16*
2.Anxiety comes from fear and fear comes from aversion,a way to counter act aversion is by practicing metta bhavana (to yourself First,make sure you spend a lot of time on yourself,lack of self confidence masks self hatred).
3.Counteract Fear by developing one of the five spiritual faculties,Faith.Take refuge in the Triple Gem,Take refuge in the Present Moment.Embrace the present moment.Anxious or not.Don't fight it or get upset that you got anxious.This just makes it worse.Just note it.Anxiety.Be present for it.Hold it in Awareness and compassion.Yes you might feel worse or uncomfortable but that's okay.You can note.Uncomfortable.No matter what arises due to insecurity to anxiety you can always Note.Which means there is something bigger than anxiety and that is Mindfulness.And soo you will see it changes.So have faith in the Buddha's teaching,put it to practice and see for yourself.
Not sure in which sutta, but I remember Buddha having been asked a similar question, about timidity, I think in Anguttara Nikaya.
His answer was, basically, that confidence comes from skill. If one is well-learned and well-trained at whatever s/he is doing, one tends to be more confident than an incompetent bumbler. The examples of skills Buddha gave were speaking, manners (posture/walking/standing/sitting), and knowledge of Dharma (he was talking about bhikkhu elders being confident at teaching Dharma, if I remember correctly).
Chogyam Trungpa compared Buddhist training to taming a gorilla. The first stage is to learn to move around without breaking stuff and hurting oneself and people. In Trungpa's interpretation, this is essentially what Sila (Shila) is, a practice of discipline, or warrior-like simplicity, cultivation of lifestyle opposite to indulging. This matures into efficient action devoid of any unnecessary/unproductive wavering.
From my own experience I can add, regular meditation helps tremendously to reduce the pathological kinds of self-reflection.
I agree with the commenters above and I want to add that insecurity is a state of mind and thus it has the properties of anicca (impermanence), anatta (insubstantiality) and dukkha (causing suffering).
The practice of vipassana trains us to see our states of mind as they arise and cease and not to cling to them. Once we learn to let them go, we realise they are not "me", they are not "mine": we simply witness the ups and downs of the mind without identifying with them and without getting upset with them.