{
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        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"
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          "defaultStatus": "unaffected",
          "modules": [
            "\u0027Elixir.MPP.Methods.Tempo\u0027"
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          "packageName": "mpp",
          "packageURL": "pkg:hex/mpp",
          "product": "mpp",
          "programFiles": [
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          "programRoutines": [
            {
              "name": "\u0027Elixir.MPP.Methods.Tempo\u0027:verify/2"
            }
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          "repo": "https://github.com/ZenHive/mpp",
          "vendor": "ZenHive",
          "versions": [
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              "lessThan": "0.16.2",
              "status": "affected",
              "version": "0.2.0",
              "versionType": "semver"
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          "collectionURL": "https://github.com",
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          "defaultStatus": "unaffected",
          "modules": [
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          "packageName": "zenhive/mpp",
          "packageURL": "pkg:github/zenhive/mpp",
          "product": "mpp",
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            "lib/mpp/methods/tempo.ex"
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          "programRoutines": [
            {
              "name": "\u0027Elixir.MPP.Methods.Tempo\u0027:verify/2"
            }
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          "repo": "https://github.com/ZenHive/mpp",
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          "versions": [
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              "status": "affected",
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              "versionType": "git"
            }
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          "lang": "en",
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              "value": "\u003cp\u003eReachable when \u003ccode\u003eMPP.Methods.Tempo\u003c/code\u003e broadcasts a \u003ccode\u003etype=\"transaction\"\u003c/code\u003e credential with a dedup store in place. From mpp 0.7.0 the dedup store is on by default (the app-started \u003ccode\u003eMPP.Tempo.ConCacheStore\u003c/code\u003e; opt out with \u003ccode\u003estore: false\u003c/code\u003e), so every default Tempo deployment from 0.7.0 before 0.16.2 is affected. Before 0.7.0 the default store was \u003ccode\u003enil\u003c/code\u003e, which runs the library statelessly and provides no application-level replay protection at all, a documented property rather than part of this issue; those versions are affected only where a \u003ccode\u003e\"store\"\u003c/code\u003e was configured explicitly in \u003ccode\u003emethod_config\u003c/code\u003e.\u003c/p\u003e"
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              "value": "Reachable when `MPP.Methods.Tempo` broadcasts a `type=\"transaction\"` credential with a dedup store in place. From mpp 0.7.0 the dedup store is on by default (the app-started `MPP.Tempo.ConCacheStore`; opt out with `store: false`), so every default Tempo deployment from 0.7.0 before 0.16.2 is affected. Before 0.7.0 the default store was `nil`, which runs the library statelessly and provides no application-level replay protection at all, a documented property rather than part of this issue; those versions are affected only where a `\"store\"` was configured explicitly in `method_config`."
            }
          ],
          "value": "Reachable when MPP.Methods.Tempo broadcasts a type=\"transaction\" credential with a dedup store in place. From mpp 0.7.0 the dedup store is on by default (the app-started MPP.Tempo.ConCacheStore; opt out with store: false), so every default Tempo deployment from 0.7.0 before 0.16.2 is affected. Before 0.7.0 the default store was nil, which runs the library statelessly and provides no application-level replay protection at all, a documented property rather than part of this issue; those versions are affected only where a \"store\" was configured explicitly in method_config."
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "0.16.2",
                  "versionStartIncluding": "0.2.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
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          ],
          "operator": "AND"
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      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "E.FU"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "E.FU"
        },
        {
          "lang": "en",
          "type": "coordinator",
          "value": "Jonatan M\u00e4nnchen / EEF"
        }
      ],
      "dateAssigned": "2026-09-15T15:20:56.000Z",
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
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              "value": "\u003cp\u003eImproper Validation of Unsafe Equivalence in Input in ZenHive mpp allows an unauthenticated remote client to pass the Tempo duplicate-submission gate twice with one signed transaction.\u003c/p\u003e\n\u003cp\u003e\u003ccode\u003eMPP.Methods.Tempo\u003c/code\u003e reserves the pre-broadcast dedup slot on the caller-supplied hex in \u003ccode\u003ereserve_hash_atomic/2\u003c/code\u003e, keyed through \u003ccode\u003estore_key/1\u003c/code\u003e on \u003ccode\u003etx.raw\u003c/code\u003e rather than on a canonical form of the transaction. The deserializer stores the caller\u0027s hex verbatim and accepts both recovery-id encodings, so one signed transaction submitted once with \u003ccode\u003ev=27\u003c/code\u003e and once with \u003ccode\u003ev=0\u003c/code\u003e yields two distinct reserve keys, and both pass the reserve and reach the broadcast path. The plug-level credential replay store is deliberately carved out for \u003ccode\u003etempo\u003c/code\u003e in \u003ccode\u003elib/mpp/replay.ex\u003c/code\u003e, leaving this reserve as the only gate, and the post-broadcast mark writes the canonical hash key that the raw-keyed reserve never reads.\u003c/p\u003e\n\u003cp\u003eWhat the duplicate submission yields depends on the node: a nonce-reuse rejection fails closed, while a node that answers with the canonical hash for an already-known transaction returns a second valid \u003ccode\u003ePayment-Receipt\u003c/code\u003e for a single on-chain payment.\u003c/p\u003e\n\u003cp\u003eThis issue affects mpp: from 0.2.0 before 0.16.2.\u003c/p\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "Improper Validation of Unsafe Equivalence in Input in ZenHive mpp allows an unauthenticated remote client to pass the Tempo duplicate-submission gate twice with one signed transaction.\n\n`MPP.Methods.Tempo` reserves the pre-broadcast dedup slot on the caller-supplied hex in `reserve_hash_atomic/2`, keyed through `store_key/1` on `tx.raw` rather than on a canonical form of the transaction. The deserializer stores the caller\u0027s hex verbatim and accepts both recovery-id encodings, so one signed transaction submitted once with `v=27` and once with `v=0` yields two distinct reserve keys, and both pass the reserve and reach the broadcast path. The plug-level credential replay store is deliberately carved out for `tempo` in `lib/mpp/replay.ex`, leaving this reserve as the only gate, and the post-broadcast mark writes the canonical hash key that the raw-keyed reserve never reads.\n\nWhat the duplicate submission yields depends on the node: a nonce-reuse rejection fails closed, while a node that answers with the canonical hash for an already-known transaction returns a second valid `Payment-Receipt` for a single on-chain payment.\n\nThis issue affects mpp: from 0.2.0 before 0.16.2."
            }
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          "value": "Improper Validation of Unsafe Equivalence in Input in ZenHive mpp allows an unauthenticated remote client to pass the Tempo duplicate-submission gate twice with one signed transaction.\n\nMPP.Methods.Tempo reserves the pre-broadcast dedup slot on the caller-supplied hex in reserve_hash_atomic/2, keyed through store_key/1 on tx.raw rather than on a canonical form of the transaction. The deserializer stores the caller\u0027s hex verbatim and accepts both recovery-id encodings, so one signed transaction submitted once with v=27 and once with v=0 yields two distinct reserve keys, and both pass the reserve and reach the broadcast path. The plug-level credential replay store is deliberately carved out for tempo in lib/mpp/replay.ex, leaving this reserve as the only gate, and the post-broadcast mark writes the canonical hash key that the raw-keyed reserve never reads.\n\nWhat the duplicate submission yields depends on the node: a nonce-reuse rejection fails closed, while a node that answers with the canonical hash for an already-known transaction returns a second valid Payment-Receipt for a single on-chain payment.\n\nThis issue affects mpp: from 0.2.0 before 0.16.2."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-267",
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            {
              "lang": "en",
              "supportingMedia": [
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                  "value": "\u003cp\u003eA client re-encodes the recovery id of a transaction it has already submitted and presents it again. The duplicate passes the only duplicate-submission gate the Tempo method has, and against a node that answers with the canonical hash for an already-known transaction the client is issued a second \u003ccode\u003ePayment-Receipt\u003c/code\u003e for one on-chain payment.\u003c/p\u003e"
                },
                {
                  "base64": false,
                  "type": "text/markdown",
                  "value": "A client re-encodes the recovery id of a transaction it has already submitted and presents it again. The duplicate passes the only duplicate-submission gate the Tempo method has, and against a node that answers with the canonical hash for an already-known transaction the client is issued a second `Payment-Receipt` for one on-chain payment."
                }
              ],
              "value": "A client re-encodes the recovery id of a transaction it has already submitted and presents it again. The duplicate passes the only duplicate-submission gate the Tempo method has, and against a node that answers with the canonical hash for an already-known transaction the client is issued a second Payment-Receipt for one on-chain payment."
            }
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        }
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      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "LOW",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
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              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-1289",
              "description": "CWE-1289 Improper Validation of Unsafe Equivalence in Input",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
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      "providerMetadata": {
        "dateUpdated": "2026-09-16T08:24:40.446Z",
        "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "shortName": "EEF"
      },
      "references": [
        {
          "name": "GitHub Advisory",
          "tags": [
            "related",
            "vendor-advisory"
          ],
          "url": "https://github.com/ZenHive/mpp/security/advisories/GHSA-8x7x-5j8g-8hcx"
        },
        {
          "name": "EEF CNA record for CVE-2026-88255",
          "tags": [
            "related"
          ],
          "url": "https://cna.erlef.org/cves/CVE-2026-88255.html"
        },
        {
          "name": "OSV record EEF-CVE-2026-88255",
          "tags": [
            "related"
          ],
          "url": "https://osv.dev/vulnerability/EEF-CVE-2026-88255"
        },
        {
          "name": "Introducing commit f890466 in ZenHive/mpp",
          "tags": [
            "related"
          ],
          "url": "https://github.com/ZenHive/mpp/commit/f8904666061fbab695874856d8fcd02c471dfe1b"
        },
        {
          "name": "Fix commit e12bd4a in ZenHive/mpp",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/ZenHive/mpp/commit/e12bd4a1cea2e97c2a01fc059c48e5594a7b4a43"
        }
      ],
      "source": {
        "discovery": "INTERNAL"
      },
      "title": "mpp Tempo keys its pre-broadcast dedup reserve on the caller-supplied transaction encoding, so a re-encoded signed transaction reserves a second slot"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
    "assignerShortName": "EEF",
    "cveId": "CVE-2026-88255",
    "datePublished": "2026-09-16T08:24:40.446Z",
    "dateReserved": "2026-09-11T18:30:01.336Z",
    "dateUpdated": "2026-09-16T08:24:40.446Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-88255\",\"sourceIdentifier\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\",\"published\":\"2026-09-16T09:17:07.333\",\"lastModified\":\"2026-09-16T09:17:07.333\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Improper Validation of Unsafe Equivalence in Input in ZenHive mpp allows an unauthenticated remote client to pass the Tempo duplicate-submission gate twice with one signed transaction.\\n\\nMPP.Methods.Tempo reserves the pre-broadcast dedup slot on the caller-supplied hex in reserve_hash_atomic/2, keyed through store_key/1 on tx.raw rather than on a canonical form of the transaction. The deserializer stores the caller\u0027s hex verbatim and accepts both recovery-id encodings, so one signed transaction submitted once with v=27 and once with v=0 yields two distinct reserve keys, and both pass the reserve and reach the broadcast path. The plug-level credential replay store is deliberately carved out for tempo in lib/mpp/replay.ex, leaving this reserve as the only gate, and the post-broadcast mark writes the canonical hash key that the raw-keyed reserve never reads.\\n\\nWhat the duplicate submission yields depends on the node: a nonce-reuse rejection fails closed, while a node that answers with the canonical hash for an already-known transaction returns a second valid Payment-Receipt for a single on-chain payment.\\n\\nThis issue affects mpp: from 0.2.0 before 0.16.2.\"}],\"affected\":[{\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\",\"affectedData\":[{\"vendor\":\"ZenHive\",\"product\":\"mpp\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://repo.hex.pm\",\"packageName\":\"mpp\",\"cpes\":[\"cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*\"],\"modules\":[\"\u0027Elixir.MPP.Methods.Tempo\u0027\"],\"programFiles\":[\"lib/mpp/methods/tempo.ex\"],\"programRoutines\":[{\"name\":\"\u0027Elixir.MPP.Methods.Tempo\u0027:verify/2\"}],\"repo\":\"https://github.com/ZenHive/mpp\",\"packageURL\":\"pkg:hex/mpp\",\"versions\":[{\"version\":\"0.2.0\",\"lessThan\":\"0.16.2\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"ZenHive\",\"product\":\"mpp\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://github.com\",\"packageName\":\"zenhive/mpp\",\"cpes\":[\"cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*\"],\"modules\":[\"\u0027Elixir.MPP.Methods.Tempo\u0027\"],\"programFiles\":[\"lib/mpp/methods/tempo.ex\"],\"programRoutines\":[{\"name\":\"\u0027Elixir.MPP.Methods.Tempo\u0027:verify/2\"}],\"repo\":\"https://github.com/ZenHive/mpp\",\"packageURL\":\"pkg:github/zenhive/mpp\",\"versions\":[{\"version\":\"f8904666061fbab695874856d8fcd02c471dfe1b\",\"lessThan\":\"e12bd4a1cea2e97c2a01fc059c48e5594a7b4a43\",\"versionType\":\"git\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X\",\"baseScore\":6.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"PRESENT\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"LOW\",\"vulnAvailabilityImpact\":\"NONE\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}]},\"weaknesses\":[{\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-1289\"}]}],\"references\":[{\"url\":\"https://cna.erlef.org/cves/CVE-2026-88255.html\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"},{\"url\":\"https://github.com/ZenHive/mpp/commit/e12bd4a1cea2e97c2a01fc059c48e5594a7b4a43\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"},{\"url\":\"https://github.com/ZenHive/mpp/commit/f8904666061fbab695874856d8fcd02c471dfe1b\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"},{\"url\":\"https://github.com/ZenHive/mpp/security/advisories/GHSA-8x7x-5j8g-8hcx\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"},{\"url\":\"https://osv.dev/vulnerability/EEF-CVE-2026-88255\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"}]}}"
  }
}