  We show that the single-server computational PIR protocol proposed by
Holzbaur, Hollanti and Wachter-Zeh in 2020 is not private, in the sense that
the server can recover in polynomial time the index of the desired file with
very high probability. The attack relies on the following observation. Removing
rows of the query matrix corresponding to the desired file yields a large
decrease of the dimension over $\mathbb{F}_q$ of the vector space spanned by
the rows of this punctured matrix. Such a dimension loss only shows up with
negligible probability when rows unrelated to the requested file are deleted.
