CVE-2026-48691

{"id": "CVE-2026-48691", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 9.8, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 3.9}, {"type": "Secondary", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.3, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "LOW", "privilegesRequired": "NONE", "confidentialityImpact": "LOW"}, "impactScore": 3.4, "exploitabilityScore": 3.9}]}, "published": "2026-05-26T17:16:53.670", "references": [{"url": "https://github.com/pavel-odintsov/fastnetmon", "tags": ["Product"], "source": "cve@mitre.org"}, {"url": "https://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp", "tags": ["Product"], "source": "cve@mitre.org"}, {"url": "https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48691-bgp-as-path-overflow", "tags": ["Third Party Advisory"], "source": "cve@mitre.org"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-190"}]}, {"type": "Secondary", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "description": [{"lang": "en", "value": "CWE-122"}, {"lang": "en", "value": "CWE-190"}]}], "descriptions": [{"lang": "en", "value": "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->as_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 > 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."}], "lastModified": "2026-05-27T21:16:19.090", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:pavel-odintsov:fastnetmon:*:*:*:*:community:*:*:*", "vulnerable": true, "matchCriteriaId": "E712A01F-3AD7-4CC2-9A8B-F8C63756EBBF", "versionEndIncluding": "1.2.9"}], "operator": "OR"}]}], "sourceIdentifier": "cve@mitre.org"}