{"id":"DEBIAN-CVE-2026-48693","details":"FastNetMon Community Edition through 1.2.9 is vulnerable to a local symlink attack via predictable file paths in /tmp. The statistics file path defaults to '/tmp/fastnetmon.dat' (src/fastnetmon.cpp line 159). The print_screen_contents_into_file() function (src/fastnetmon_logic.cpp line 2186) opens this path with std::ios::trunc without checking for symlinks or using O_NOFOLLOW. Additionally, the chmod() call on line 2190 always operates on cli_stats_file_path regardless of which file_path parameter was passed (a bug that applies wrong permissions), and the umask is set to 0 during daemonization (src/fastnetmon.cpp line 1821), making all created files world-writable. A local attacker can exploit this to overwrite arbitrary files as the FastNetMon process user (typically root).","modified":"2026-09-14T17:03:16.835417558Z","published":"2026-05-26T17:16:53.807Z","upstream":["CVE-2026-48693"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-48693"}],"affected":[{"package":{"name":"fastnetmon","ecosystem":"Debian:12","purl":"pkg:deb/debian/fastnetmon?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.4-2","1.2.4-2+deb12u1","1.2.5-1","1.2.5-2","1.2.5-2~bpo12+1","1.2.6-1","1.2.6-1~bpo12+1","1.2.7-1","1.2.7-1~bpo12+1","1.2.8+git20250911-1","1.2.8+git20250911-2","1.2.8-1","1.2.8-1~bpo12+1","1.2.9-1"],"ecosystem_specific":{"urgency":"unimportant"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48693.json"}},{"package":{"name":"fastnetmon","ecosystem":"Debian:13","purl":"pkg:deb/debian/fastnetmon?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.8+git20250911-1","1.2.8+git20250911-2","1.2.8-1","1.2.9-0+deb13u1","1.2.9-1"],"ecosystem_specific":{"urgency":"unimportant"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48693.json"}},{"package":{"name":"fastnetmon","ecosystem":"Debian:14","purl":"pkg:deb/debian/fastnetmon?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.8+git20250911-1","1.2.8+git20250911-2","1.2.8-1","1.2.9-1"],"ecosystem_specific":{"urgency":"unimportant"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48693.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N"}]}