An arbitrary file write vulnerability was found in GNU gzip's zgrep utility. When zgrep is applied on the attacker's chosen file name (for example a crafted file name) this can overwrite an attacker's content to an arbitrary attacker-selected file. This flaw occurs due to insufficient validation when processing filenames with two or more newlines where selected content and the target file names are embedded in crafted multi-line file names. This flaw allows a remote low privileged attacker to force zgrep to write arbitrary files on the system.