Debusine is an integrated solution to build, distribute and maintain a Debian-based distribution. Debian source packages (.dsc) and upload artifacts (.changes) are manifest files that name the files that make up the artifact. The parser used to read these files in Debusine accepted arbitrary fully user-controlled paths. The mergeuploads task could be abused to create arbitrary symbolic links on a worker, overwriting any file that the worker user has access to.