Arbitrary Root Code Execution via Directory Traversal in pacman

CVE-2019-9686 · HIGH Severity

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

pacman before 5.1.3 allows directory traversal when installing a remote package via a specified URL "pacman -U <url>" due to an unsanitized file name received from a Content-Disposition header. pacman renames the downloaded package file to match the name given in this header. However, pacman did not sanitize this name, which may contain slashes, before calling rename(). A malicious server (or a network MitM if downloading over HTTP) can send a Content-Disposition header to make pacman place the file anywhere in the filesystem, potentially leading to arbitrary root code execution. Notably, this bypasses pacman's package signature checking. This occurs in curl_download_internal in lib/libalpm/dload.c.

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