Official standard design of the Historical national (armorial) flag of Lithuania (name according to [1]).
Source: [2].

My corrections: removed borders, figure size and positioning according to the description, cleanup (removed 'trash' objects and reduced nodes), converted colors from CMYK to RGB (black, blue, and yellow according to [3], red according to [4]).
Transferred from lt.wikipedia to Commons.
The original uploader was Jefim Vytovtov at Lithuanian Wikipedia.