Vulnerability-Lookup

GHSA-P7V4-JPP9-2M3Q

Vulnerability from github – Published: 2026-09-16 09:30 – Updated: 2026-09-16 09:30

Details

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.

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's 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.

What 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.

This issue affects mpp: from 0.2.0 before 0.16.2.

Severity

6.3 (Medium)


                  
                    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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-88255"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1289"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-16T09:17:07Z",
    "severity": "MODERATE"
  },
  "details": "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.",
  "id": "GHSA-p7v4-jpp9-2m3q",
  "modified": "2026-09-16T09:30:29Z",
  "published": "2026-09-16T09:30:29Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ZenHive/mpp/security/advisories/GHSA-8x7x-5j8g-8hcx"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-88255"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ZenHive/mpp/commit/e12bd4a1cea2e97c2a01fc059c48e5594a7b4a43"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ZenHive/mpp/commit/f8904666061fbab695874856d8fcd02c471dfe1b"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-88255.html"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-88255"
    }
  ],
  "schema_version": "1.4.0",
  "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/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",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-88255 (GCVE-0-2026-88255)

Vulnerability from cvelistv5 – Published: 2026-09-16 08:24 – Updated: 2026-09-16 08:24

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

Summary

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. 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's 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. What 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. This issue affects mpp: from 0.2.0 before 0.16.2.

Severity

6.3 (Medium)


                        
                          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

CWE

CWE-1289 - Improper Validation of Unsafe Equivalence in Input

Assigner

EEF mitre root

References

5 references

URL	Tags
https://github.com/ZenHive/mpp/security/advisorie…	relatedvendor-advisory
https://cna.erlef.org/cves/CVE-2026-88255.html	related
https://osv.dev/vulnerability/EEF-CVE-2026-88255	related
https://github.com/ZenHive/mpp/commit/f8904666061…	related
https://github.com/ZenHive/mpp/commit/e12bd4a1cea…	patch

Impacted products

2 products

Vendor	Product	Version
ZenHive	mpp	Affected: 0.2.0 , < 0.16.2 (semver) cpe:2.3:a:ZenHive:mpp::::::::
ZenHive	mpp	Affected: f8904666061fbab695874856d8fcd02c471dfe1b , < e12bd4a1cea2e97c2a01fc059c48e5594a7b4a43 (git) cpe:2.3:a:ZenHive:mpp::::::::

Credits

E.FU E.FU Jonatan Männchen / EEF

Show details on NVD website

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          "collectionURL": "https://repo.hex.pm",
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          "packageURL": "pkg:hex/mpp",
          "product": "mpp",
          "programFiles": [
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          "programRoutines": [
            {
              "name": "\u0027Elixir.MPP.Methods.Tempo\u0027:verify/2"
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          "programFiles": [
            "lib/mpp/methods/tempo.ex"
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          "programRoutines": [
            {
              "name": "\u0027Elixir.MPP.Methods.Tempo\u0027:verify/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\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": "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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            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
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            "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",
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            "vulnerabilityResponseEffort": "NOT_DEFINED"
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      "providerMetadata": {
        "dateUpdated": "2026-09-16T08:24:40.446Z",
        "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "shortName": "EEF"
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          "name": "GitHub Advisory",
          "tags": [
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            "vendor-advisory"
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          "tags": [
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        },
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        {
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          "tags": [
            "related"
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      ],
      "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",
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    "datePublished": "2026-09-16T08:24:40.446Z",
    "dateReserved": "2026-09-11T18:30:01.336Z",
    "dateUpdated": "2026-09-16T08:24:40.446Z",
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.