{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.2.0"
              },
              {
                "fixed": "0.6.1"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "7ca7538f05959a98e0e5e63e4bd949b4f362cf8d"
            },
            {
              "fixed": "542a525563c2fcedd670b593437deca81c6797a4"
            },
            {
              "fixed": "46c5b0e1311da7d92190dc7d9ea89027a1d365e9"
            }
          ],
          "repo": "https://github.com/zenhive/mpp",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-w8j7-7qc3-5f24"
  ],
  "database_specific": {
    "cna_assigner": "EEF",
    "cwe_ids": [
      "CWE-367"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73829.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "introduced": "f8904666061fbab695874856d8fcd02c471dfe1b"
          },
          {
            "fixed": "46c5b0e1311da7d92190dc7d9ea89027a1d365e9"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "Time-of-check Time-of-use (TOCTOU) Race Condition in ZenHive mpp allows an unauthenticated remote client to redeem one confirmed on-chain payment for multiple paid-resource accesses.\n\nThe type=\"hash\" credential path in MPP.Methods.Tempo.verify/2 guards against replay with a non-atomic check-then-mark sequence: check_hash_unused/2 reads the dedup store, an eth_getTransactionReceipt round trip verifies the payment on chain, and only then does mark_hash_used/2 write the mark. Concurrent requests carrying the same settled payment hash all pass the read before any of them writes, so each is issued a receipt. The store's atomic check_and_mark/2 primitive is available and used by the type=\"transaction\" path, but the hash path calls plain get and put even when the configured store implements it. Exploitation requires a dedup store to be configured; the default nil store is stateless and documented as offering no replay protection at all.\n\nThis issue affects mpp: from 0.2.0 before 0.6.1.",
  "id": "CVE-2026-73829",
  "modified": "2026-08-21T03:30:25.477685697Z",
  "published": "2026-08-19T17:19:43.696Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-73829.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-73829"
    },
    {
      "type": "WEB",
      "url": "https://repo.hex.pm"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73829.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/ZenHive/mpp/security/advisories/GHSA-w8j7-7qc3-5f24"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-73829"
    },
    {
      "type": "FIX",
      "url": "https://github.com/ZenHive/mpp/commit/46c5b0e1311da7d92190dc7d9ea89027a1d365e9"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ZenHive/mpp"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Non-atomic hash-credential dedup in mpp Tempo allows replay of a confirmed payment under a concurrent race"
}