OSEC-2023-01 Time of check time of use issue in opam's cache

Bug description Opam uses since version 2.0.0 a download cache: if a source artifact is needed, first its hash is looked up in the local cache /.opam/download-cache//. Opam supports multiple hash algorithms, a cache lookup tries all hash algorithms present in the opam file. Before opam 2.1.5, the...