S3QL before 2.27 mishandles checksumming, and consequently allows replay attacks in which an attacker who controls the backend can present …

S3QL before 2.27 mishandles checksumming, and consequently allows replay attacks in which an attacker who controls the backend can present old versions of the filesystem metadata database as up-to-date, temporarily inject zero-valued bytes into files, or temporarily hide parts of files. This is related to the checksum_basic_mapping function.