{"id":"DEBIAN-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":"2026-09-14T17:03:16.126606335Z","published":"2026-05-26T17:16:53.670Z","upstream":["CVE-2026-48691"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-48691"}],"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-2026-48691.json"}},{"package":{"name":"fastnetmon","ecosystem":"Debian:13","purl":"pkg:deb/debian/fastnetmon?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.2.9-0+deb13u1"}]}],"versions":["1.2.8+git20250911-1","1.2.8+git20250911-2","1.2.8-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48691.json"}},{"package":{"name":"fastnetmon","ecosystem":"Debian:14","purl":"pkg:deb/debian/fastnetmon?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.2.9-1"}]}],"versions":["1.2.8+git20250911-1","1.2.8+git20250911-2","1.2.8-1"],"ecosystem_specific":{"urgency":"unimportant"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48691.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}