CoCoS attested TLS is vulnerable to relay attacks via extracted ephemeral TLS keys

{
  "id": "79d00249051d6120fbf6057e0a2a6fba10acfb02cecddff679f3de95927e44fb",
  "url": "https://osv.dev/vulnerability/CVE-2026-33697",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CoCoS attested TLS is vulnerable to relay attacks via extracted ephemeral TLS keys",
    "summary": "Cocos AI is a confidential computing system for AI. The current implementation of attested TLS (aTLS) in CoCoS is vulnerable to a relay attack affecting all versions from v0.4.0 through v0.8.2. This vulnerability is present in both the AMD SEV-SNP and Intel TDX deployment targets supported by CoCoS. In the affected design, an attacker may be able to extract the ephemeral TLS private key used during the intra-handshake attestation. Because the attestation evidence is bound to the ephemeral key but not to the TLS channel, possession of that key is sufficient to relay or divert the attested TLS session. A client will accept the connection under false assumptions about the endpoint it is communicating with — the attestation report cannot distinguish the genuine attested service from the attacker's relay. This undermines the intended authentication guarantees of attested TLS. A successful attack may allow an attacker to impersonate an attested CoCoS service and access data or operations that the client intended to send only to the genuine attested endpoint. Exploitation requires the attacker to first extract the ephemeral TLS private key, which is possible through physical access to the server hardware, transient execution attacks, or side-channel attacks. Note that the aTLS implementation was fully redesigned in v0.7.0, but the redesign does not address this vulnerability. The relay attack weakness is architectural and affects all releases in the v0.4.0–v0.8.2 range. This vulnera",
    "evidence": "osv:CVE-2026-33697",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-33697",
      "aliases": [
        "CVE-2026-33697",
        "GHSA-vfgg-mvxx-mgg7"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/ultravioletrs/cocos",
              "type": "GIT",
              "events": [
                {
                  "introduced": "10037ad874578a97bca71bbf80ca6e7298c00a21"
                },
                {
                  "fixed": "de8e198b718750b95d2a7b68c2806df8b90b5c37"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0.4.0"
                      },
                      {
                        "fixed": "0.8.2"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:ultraviolet:cocos_ai:*:*:*:*:*:go:*:*",
                    "range": [
                      {
                        "introduced": "0.4.0"
                      },
                      {
                        "fixed": "0.9.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.8.1",
            "v0.8.0",
            "v0.7.0",
            "v0.6.0",
            "v0.5.2",
            "v0.5.1",
            "v0.5.0",
            "v0.4.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-33697.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:45.789215790Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33697.json",
        "https://github.com/ultravioletrs/cocos/security/advisories/GHSA-vfgg-mvxx-mgg7",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-33697"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-322",
          "CWE-346"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33697.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-33697",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 513734,
  "published_at": "2026-03-26T23:34:53.414+00:00"
}