eef-cve-2026-87119

{
  "affected": [
    {
      "database_specific": {
        "source": "https://cna.erlef.org/osv/EEF-CVE-2026-87119.json"
      },
      "package": {
        "ecosystem": "Hex",
        "name": "mpp",
        "purl": "pkg:hex/mpp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.14.0"
            },
            {
              "fixed": "0.16.2"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": [
        "0.14.0",
        "0.15.0",
        "0.16.0",
        "0.16.1"
      ]
    },
    {
      "database_specific": {
        "source": "https://cna.erlef.org/osv/EEF-CVE-2026-87119.json"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "db464dfa9a86ccda58f0827101f6da6bd8aafa78"
            },
            {
              "fixed": "4b6eaec02af0e8485cfb4ff68f467d075ed5dd6f"
            }
          ],
          "repo": "https://github.com/ZenHive/mpp",
          "type": "GIT"
        }
      ],
      "versions": [
        "v0.16.1",
        "v0.16.0",
        "v0.15.0",
        "v0.14.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-87119",
    "GHSA-p9fv-9w58-95x2"
  ],
  "credits": [
    {
      "name": "E.FU",
      "type": "FINDER"
    },
    {
      "name": "E.FU",
      "type": "REMEDIATION_DEVELOPER"
    },
    {
      "name": "Jonatan Männchen / EEF",
      "type": "COORDINATOR"
    }
  ],
  "database_specific": {
    "capec_ids": [
      "CAPEC-60"
    ],
    "cpe_ids": [
      "cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"
    ],
    "cwe_ids": [
      "CWE-294"
    ]
  },
  "details": "## Summary\n\nAuthentication Bypass by Capture-replay in ZenHive mpp allows an attacker holding a captured subscription activation credential to charge the payer repeatedly.\n\nThe payer signs a Tempo `KeyAuthorization` over the chain id, key type, key id, expiry, limits and scopes only, with nothing tying it to the challenge that prompted it. `MPP.Methods.Tempo.KeyAuthorization.verify/3` in `lib/mpp/methods/tempo/key_authorization.ex` pins each of those signed fields against the subscription request, and the access key it pins is a static per-endpoint server key, so one signed authorization verifies against every challenge the server issues for the same subscription terms. `MPP.Methods.Tempo.Subscription.activate/4` deduplicates activations by challenge id, so presenting the captured credential under a fresh challenge produces a different dedup key, `claim_activation` succeeds, and the subscription transaction is built and broadcast again. Each replay charges the payer's wallet a new first-period settlement and re-authorizes the server key, bounded only by the subscription expiry and the chain's own semantics for re-installing an existing key.\n\nThis issue affects mpp: from 0.14.0 before 0.16.2.\n\n## Impact\n\nAn attacker who obtains a payer's subscription activation credential (from a non-TLS hop, a log, a compromised intermediary, or the client's own retry buffer) can present it under fresh challenges to settle repeated first-period charges against that payer's wallet and re-authorize the server's access key. The payer bears the on-chain cost, limited only by the per-period subscription limit and the subscription expiry.\n\n## Configurations\n\nOnly deployments offering Tempo subscriptions are affected, which requires `subscription_access_key_private_key` in the Tempo `method_config`. Exploitation further requires the attacker to have obtained a payer's signed activation credential, in transit over a hop that is not TLS-protected or at rest in a log, an intermediary, or a client retry buffer.",
  "id": "EEF-CVE-2026-87119",
  "modified": "2026-09-22T11:40:55.168831655Z",
  "published": "2026-09-22T11:16:56.232Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/ZenHive/mpp/security/advisories/GHSA-p9fv-9w58-95x2"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-87119.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ZenHive/mpp/commit/db464dfa9a86ccda58f0827101f6da6bd8aafa78"
    },
    {
      "type": "FIX",
      "url": "https://github.com/ZenHive/mpp/commit/4b6eaec02af0e8485cfb4ff68f467d075ed5dd6f"
    },
    {
      "type": "PACKAGE",
      "url": "https://hex.pm/packages/mpp"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "mpp Tempo subscription key authorization is not bound to the issuing challenge, allowing a captured activation credential to be replayed"
}