HCSEC-2026-35 - Consul vulnerable to a denial of service in the native RPC listener

{
  "id": "28eaaaf5ed260f5cea4cd2ac2be6f9e60547a62e0b80db08c07e04bda3389511",
  "url": "https://discuss.hashicorp.com/t/hcsec-2026-35-consul-vulnerable-to-a-denial-of-service-in-the-native-rpc-listener/77737",
  "method": "llm",
  "payload": {
    "kind": "patch",
    "title": "HCSEC-2026-35 - Consul vulnerable to a denial of service in the native RPC listener",
    "summary": "An authenticated client able to complete the internal RPC mTLS handshake can cause excessive server memory consumption before ACL authorization. No ACL token is required. Upgrade to a fixed version.",
    "evidence": "A client that can complete the internal RPC mTLS handshake may exploit this issue without holding a valid ACL token.",
    "products": [
      {
        "name": {
          "value": "Consul",
          "evidence": "Consul and Consul Enterprise 1.21.0 through 2.0.3; fixed in Consul 2.0.4"
        },
        "prerequisites": [
          {
            "value": "complete the internal RPC mTLS handshake",
            "evidence": "A client that can complete the internal RPC mTLS handshake may exploit this issue without holding a valid ACL token."
          }
        ],
        "fixed_versions": [
          {
            "value": "2.0.4",
            "evidence": "fixed in Consul 2.0.4"
          }
        ],
        "affected_versions": [
          {
            "value": "1.21.0 through 2.0.3",
            "evidence": "Consul and Consul Enterprise 1.21.0 through 2.0.3; fixed in Consul 2.0.4"
          }
        ]
      },
      {
        "name": {
          "value": "Consul Enterprise",
          "evidence": "Consul and Consul Enterprise 1.21.0 through 2.0.3; fixed in Consul 2.0.4 and Consul Enterprise 1.21.18, 1.22.12, and 2.0.4."
        },
        "prerequisites": [
          {
            "value": "complete the internal RPC mTLS handshake",
            "evidence": "A client that can complete the internal RPC mTLS handshake may exploit this issue without holding a valid ACL token."
          }
        ],
        "fixed_versions": [
          {
            "value": "1.21.18",
            "evidence": "fixed in Consul 2.0.4 and Consul Enterprise 1.21.18, 1.22.12, and 2.0.4."
          },
          {
            "value": "1.22.12",
            "evidence": "fixed in Consul 2.0.4 and Consul Enterprise 1.21.18, 1.22.12, and 2.0.4."
          },
          {
            "value": "2.0.4",
            "evidence": "fixed in Consul 2.0.4 and Consul Enterprise 1.21.18, 1.22.12, and 2.0.4."
          }
        ],
        "affected_versions": [
          {
            "value": "1.21.0 through 2.0.3",
            "evidence": "Consul and Consul Enterprise 1.21.0 through 2.0.3; fixed in Consul 2.0.4 and Consul Enterprise 1.21.18, 1.22.12, and 2.0.4."
          }
        ]
      }
    ],
    "severity": "unknown",
    "fixed_cves": [
      {
        "cve": "CVE-2026-87106",
        "product": "Consul",
        "evidence": "This vulnerability (CVE-2026-87106) is fixed in Consul 2.0.4"
      },
      {
        "cve": "CVE-2026-87106",
        "product": "Consul Enterprise",
        "evidence": "This vulnerability (CVE-2026-87106) is fixed in Consul 2.0.4 and Consul Enterprise 1.21.18, 1.22.12 and 2.0.4."
      }
    ],
    "related_cves": [
      {
        "value": "CVE-2026-87106",
        "evidence": "This vulnerability (CVE-2026-87106) is fixed in Consul 2.0.4 and Consul Enterprise 1.21.18, 1.22.12 and 2.0.4."
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "official-hashicorp-discuss-security",
  "document_id": 24007,
  "published_at": "2026-09-10T18:46:33+00:00"
}