{"id":"UBUNTU-CVE-2026-48691","details":"FastNetMon Community Edition through 1.2.9 contains an integer overflow in the BGP AS_PATH attribute encoder. In src/bgp_protocol.hpp, the IPv4UnicastAnnounce::get_attributes() function computes attribute_length as 'sizeof(bgp_as_path_segment_element_t) + this-\u003eas_path_asns.size() * sizeof(uint32_t)' and stores it in a uint8_t field (line 600-605). Since uint8_t can only hold values 0-255, an AS_PATH containing more than 63 ASNs (2 + 64*4 = 258 \u003e 255) causes silent truncation. The truncated length is used for buffer sizing, while the actual data written is the full untruncated amount, resulting in a heap buffer overflow. Similarly, the path_segment_length field at line 621 is also uint8_t, truncating with more than 255 ASNs.","modified":"2026-06-16T05:00:07.480862728Z","published":"2026-05-26T17:16:00Z","related":["USN-8429-1"],"upstream":["CVE-2026-48691"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-48691"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-48691"},{"type":"REPORT","url":"https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48691-bgp-as-path-overflow"},{"type":"REPORT","url":"https://github.com/pavel-odintsov/fastnetmon/commit/94c66d5b100c42fb8bd10a22ca595e46895d60d0"},{"type":"REPORT","url":"https://github.com/pavel-odintsov/fastnetmon/pull/1054"},{"type":"REPORT","url":"https://github.com/pavel-odintsov/fastnetmon"},{"type":"REPORT","url":"https://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8429-1"}],"affected":[{"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"},{"fixed":"1.2.6-1ubuntu0.1~esm1"}]}],"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"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro","binaries":[{"binary_version":"1.2.6-1ubuntu0.1~esm1","binary_name":"fastnetmon"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48691.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_name":"fastnetmon","binary_version":"1.2.8+git20250911-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48691.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"},{"fixed":"1.2.8+git20250911-2ubuntu0.1~esm1"}]}],"versions":["1.2.8+git20250911-1","1.2.8+git20250911-1build1","1.2.8+git20250911-1build2","1.2.8+git20250911-2"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro","binaries":[{"binary_name":"fastnetmon","binary_version":"1.2.8+git20250911-2ubuntu0.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48691.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L"},{"type":"Ubuntu","score":"medium"}]}