From Wiki: On 25 June 1950, the United Nations Security Council (UNSC) adopted Resolution 83 finding that the North Korean invasion of the Republic of Korea was a breach of the peace in violation of Chapter VII of the UN Charter. The Soviet Union, a veto-wielding power, had been boycotting the UN Security Council since January 1950 in protest of Taiwan’s occupation of China’s permanent seat. Thus, the Soviet Union’s representative was not present at the meeting and was unable to vote against the resolution.

Scholars debated whether abstaining, i.e. not actively using permanent member’s veto, means voting against a proposal or not. The current position is that permanent members can not not use their absentee ‘votes’ to block the entirety of UNSC.

MCDOUGAL, Myres S. and Richard N. GARDNER. The Veto and the Charter: An Interpretation for Survival. Yale Law Journal. 1951, vol. 60, no. 2, pp. 258–293.