{"schemaVersion":3,"id":"CVE-2026-39977","aliases":["UBUNTU-CVE-2026-39977","DEBIAN-CVE-2026-39977","openSUSE-SU-2026:10590-1"],"status":"published","duplicateOf":null,"title":null,"description":"flatpak-builder is a tool to build flatpaks from source. From 1.4.5 to before 1.4.8, the license-files manifest key takes an array of paths to user defined licence files relative to the source directory of the module. The paths from that array are resolved using g_file_resolve_relative_path() and validated to stay inside the source directory using two checks - g_file_get_relative_path() which does not resolve symlinks and g_file_query_file_type() with G_FILE_QUERY_INFO_NOFOLLOW_SYMLINKS which only applies to the final path component. The copy operation runs on host. This can be exploited by using a crafted manifest and/or source to read arbitrary files from the host and capture them into the build output. 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