{"id":"UBUNTU-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":"2026-06-15T20:15:15.366923946Z","published":"2026-05-26T17:16:00Z","upstream":["CVE-2026-48693"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-48693"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-48693"},{"type":"REPORT","url":"https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48693-symlink-tmp"},{"type":"REPORT","url":"https://github.com/pavel-odintsov/fastnetmon"},{"type":"REPORT","url":"https://github.com/pavel-odintsov/fastnetmon/blob/master/src/fastnetmon.cpp"},{"type":"REPORT","url":"https://github.com/pavel-odintsov/fastnetmon/blob/master/src/fastnetmon_logic.cpp"}],"affected":[{"package":{"name":"fastnetmon","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/fastnetmon?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.3+dfsg-3","1.1.3+dfsg-4","1.1.3+dfsg-6build1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.1.3+dfsg-6build1","binary_name":"fastnetmon"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48693.json"}},{"package":{"name":"fastnetmon","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/fastnetmon?arch=source&distro=esm-apps%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.4-1","1.1.4-1build3","1.1.4-1build4","1.1.4-1build5","1.1.4-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"fastnetmon","binary_version":"1.1.4-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48693.json"}},{"package":{"name":"fastnetmon","ecosystem":"Ubuntu:Pro:24.04:LTS","purl":"pkg:deb/ubuntu/fastnetmon?arch=source&distro=esm-apps%2Fnoble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.5-1","1.2.6-1","1.2.6-1build1","1.2.6-1build2","1.2.6-1build3","1.2.6-1build4","1.2.6-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"fastnetmon","binary_version":"1.2.6-1ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48693.json"}},{"package":{"name":"fastnetmon","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/fastnetmon?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.8-1build1","1.2.8-1build2","1.2.8+git20250911-1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.2.8+git20250911-1","binary_name":"fastnetmon"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48693.json"}},{"package":{"name":"fastnetmon","ecosystem":"Ubuntu:Pro:26.04:LTS","purl":"pkg:deb/ubuntu/fastnetmon?arch=source&distro=esm-apps%2Fresolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.8+git20250911-1","1.2.8+git20250911-1build1","1.2.8+git20250911-1build2","1.2.8+git20250911-2","1.2.8+git20250911-2ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.2.8+git20250911-2ubuntu0.1~esm1","binary_name":"fastnetmon"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48693.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N"},{"type":"Ubuntu","score":"medium"}]}