{"id":"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":"2026-08-12T03:51:18.026997928Z","published":"2026-05-26T00:00:00Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48685.json","cna_assigner":"mitre"},"references":[{"type":"WEB","url":"https://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48685.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48685"},{"type":"PACKAGE","url":"https://github.com/pavel-odintsov/fastnetmon"},{"type":"ARTICLE","url":"https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48685-bgp-extended-length"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/pavel-odintsov/fastnetmon","events":[{"introduced":"0"},{"fixed":"394fbe06d112f9609d3d1cb10d60cbf98347c96a"}],"database_specific":{"cpe":"cpe:2.3:a:pavel-odintsov:fastnetmon:*:*:*:*:community:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"1.2.9"},{"last_affected":"1.2.9"}],"source":["DESCRIPTION","CPE_RANGE"]}}],"versions":["v1.2.8","v1.2.7","v1.2.6","v1.2.5","v1.2.4","v1.2.3","v1.2.2","v1.2.1","v1.2.0","v1.1.9","v1.1.8","v1.1.7","v1.1.6","v1.1.5","v1.1.4","v1.1.3","v1.1.2","v1.1.0","v1.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-48685.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}