{"id":"UBUNTU-CVE-2026-48685","details":"FastNetMon Community Edition through 1.2.9 has out-of-bounds memory access because it incorrectly parses BGP path attributes with the extended length flag set. In src/bgp_protocol.hpp, the parse_raw_bgp_attribute() function correctly identifies when extended_length_bit is set and sets length_of_length_field to 2, but then reads only a single byte for the attribute value length (attribute_value_length = value[2] at line 173). Per RFC 4271 Section 4.3, when the Extended Length bit is set, the Attribute Length field is two octets and the value should be read as a 16-bit big-endian integer from value[2] and value[3]. As a result, any attribute longer than 255 bytes has its length silently truncated to the low byte (e.g., 300 bytes = 0x012C is read as 0x2C = 44 bytes). The remaining 256 bytes are then misinterpreted as subsequent attributes, causing cascading parse failures and potential out-of-bounds memory access.","modified":"2026-06-15T20:15:13.666755764Z","published":"2026-05-26T16:16:00Z","upstream":["CVE-2026-48685"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-48685"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-48685"},{"type":"REPORT","url":"https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48685-bgp-extended-length"},{"type":"REPORT","url":"https://github.com/pavel-odintsov/fastnetmon/commit/2bf813b2590b9847308877a65fc72df560dd282f"},{"type":"REPORT","url":"https://github.com/pavel-odintsov/fastnetmon"},{"type":"REPORT","url":"https://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp"}],"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_name":"fastnetmon","binary_version":"1.1.3+dfsg-6build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-48685.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-2026-48685.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_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-2026-48685.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-2026-48685.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_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-2026-48685.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}