{"id":"UBUNTU-CVE-2026-39977","details":"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. This vulnerability is fixed in 1.4.8.","modified":"2026-05-20T16:25:38.531287082Z","published":"2026-04-09T20:16:00Z","upstream":["CVE-2026-39977"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-39977"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-39977"},{"type":"REPORT","url":"https://github.com/flatpak/flatpak-builder/security/advisories/GHSA-6gm9-3g7m-3965"}],"affected":[{"package":{"name":"flatpak-builder","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/flatpak-builder?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.4.4-2","1.4.4-2build1","1.4.5-1","1.4.6-2"],"ecosystem_specific":{"binaries":[{"binary_version":"1.4.6-2","binary_name":"flatpak-builder"},{"binary_name":"flatpak-builder-tests","binary_version":"1.4.6-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39977.json"}},{"package":{"name":"flatpak-builder","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/flatpak-builder?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.4.8-1"}]}],"versions":["1.4.6-2","1.4.7-1"],"ecosystem_specific":{"binaries":[{"binary_name":"flatpak-builder","binary_version":"1.4.8-1"},{"binary_name":"flatpak-builder-tests","binary_version":"1.4.8-1"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-39977.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N"},{"type":"Ubuntu","score":"medium"}]}