CVE-2026-73829 (GCVE-0-2026-73829)

Vulnerability from cvelistv5 – Published: 2026-08-19 17:19 – Updated: 2026-08-19 18:58
VLAI
Title
Non-atomic hash-credential dedup in mpp Tempo allows replay of a confirmed payment under a concurrent race
Summary
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. The 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. This issue affects mpp: from 0.2.0 before 0.6.1.
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
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-19 18:55 UTC
CWE
  • CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition
Assigner
References
Impacted products
Vendor Product Version CPE status
ZenHive mpp Affected: 0.2.0 , < 0.6.1 (semver)
    cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*
Create a notification for this product.
ZenHive mpp Affected: f8904666061fbab695874856d8fcd02c471dfe1b , < 46c5b0e1311da7d92190dc7d9ea89027a1d365e9 (git)
    cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*
Create a notification for this product.
Date Public
2026-06-29 00:00
Credits
Jonatan Männchen / EEF E.FU E.FU
Show details on NVD website
To clipboard 

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      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-73829\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-08-19T18:55:14.304500Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-08-19T18:57:34.178Z\"}}], \"cna\": {\"title\": \"Non-atomic hash-credential dedup in mpp Tempo allows replay of a confirmed payment under a concurrent race\", \"source\": {\"discovery\": \"EXTERNAL\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"analyst\", \"value\": \"Jonatan M\\u00e4nnchen / EEF\"}, {\"lang\": \"en\", \"type\": \"finder\", \"value\": \"E.FU\"}, {\"lang\": \"en\", \"type\": \"remediation developer\", \"value\": \"E.FU\"}], \"impacts\": [{\"capecId\": \"CAPEC-29\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"CAPEC-29 Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions\"}]}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 6.3, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"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\", \"providerUrgency\": \"NOT_DEFINED\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"PRESENT\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"LOW\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"NONE\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\", \"vulnerabilityResponseEffort\": \"NOT_DEFINED\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"cpes\": [\"cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*\"], \"repo\": \"https://github.com/ZenHive/mpp\", \"vendor\": \"ZenHive\", \"modules\": [\"\u0027Elixir.MPP.Methods.Tempo\u0027\"], \"product\": \"mpp\", \"versions\": [{\"status\": \"affected\", \"version\": \"0.2.0\", \"lessThan\": \"0.6.1\", \"versionType\": \"semver\"}], \"packageURL\": \"pkg:hex/mpp\", \"packageName\": \"mpp\", \"programFiles\": [\"lib/mpp/methods/tempo.ex\"], \"collectionURL\": \"https://repo.hex.pm\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"\u0027Elixir.MPP.Methods.Tempo\u0027:verify/2\"}]}, {\"cpes\": [\"cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*\"], \"repo\": \"https://github.com/ZenHive/mpp\", \"vendor\": \"ZenHive\", \"modules\": [\"\u0027Elixir.MPP.Methods.Tempo\u0027\"], \"product\": \"mpp\", \"versions\": [{\"status\": \"affected\", \"version\": \"f8904666061fbab695874856d8fcd02c471dfe1b\", \"lessThan\": \"46c5b0e1311da7d92190dc7d9ea89027a1d365e9\", \"versionType\": \"git\"}], \"packageURL\": \"pkg:github/zenhive/mpp\", \"packageName\": \"zenhive/mpp\", \"programFiles\": [\"lib/mpp/methods/tempo.ex\"], \"collectionURL\": \"https://github.com\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"\u0027Elixir.MPP.Methods.Tempo\u0027:verify/2\"}]}], \"datePublic\": \"2026-06-29T00:00:00.000Z\", \"references\": [{\"url\": \"https://github.com/ZenHive/mpp/security/advisories/GHSA-w8j7-7qc3-5f24\", \"tags\": [\"vendor-advisory\", \"related\"]}, {\"url\": \"https://cna.erlef.org/cves/CVE-2026-73829.html\", \"tags\": [\"related\"]}, {\"url\": \"https://osv.dev/vulnerability/EEF-CVE-2026-73829\", \"tags\": [\"related\"]}, {\"url\": \"https://github.com/ZenHive/mpp/commit/46c5b0e1311da7d92190dc7d9ea89027a1d365e9\", \"tags\": [\"patch\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"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\u0027s 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.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eTime-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.\u003c/p\u003e\\n\u003cp\u003eThe \u003ccode\u003etype=\\\"hash\\\"\u003c/code\u003e credential path in \u003ccode\u003eMPP.Methods.Tempo.verify/2\u003c/code\u003e guards against replay with a non-atomic check-then-mark sequence: \u003ccode\u003echeck_hash_unused/2\u003c/code\u003e reads the dedup store, an \u003ccode\u003eeth_getTransactionReceipt\u003c/code\u003e round trip verifies the payment on chain, and only then does \u003ccode\u003emark_hash_used/2\u003c/code\u003e 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\u0027s atomic \u003ccode\u003echeck_and_mark/2\u003c/code\u003e primitive is available and used by the \u003ccode\u003etype=\\\"transaction\\\"\u003c/code\u003e path, but the hash path calls plain \u003ccode\u003eget\u003c/code\u003e and \u003ccode\u003eput\u003c/code\u003e even when the configured store implements it. Exploitation requires a dedup store to be configured; the default \u003ccode\u003enil\u003c/code\u003e store is stateless and documented as offering no replay protection at all.\u003c/p\u003e\\n\u003cp\u003eThis issue affects mpp: from 0.2.0 before 0.6.1.\u003c/p\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"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\u0027s 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.\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-367\", \"description\": \"CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition\"}]}], \"configurations\": [{\"lang\": \"en\", \"value\": \"The race is only reachable when MPP.Methods.Tempo is configured with a dedup store (\\\"store\\\" in method_config). The default is nil, which runs the library statelessly and provides no application-level replay protection at all, a documented property rather than part of this issue.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eThe race is only reachable when \u003ccode\u003eMPP.Methods.Tempo\u003c/code\u003e is configured with a dedup store (\u003ccode\u003e\\\"store\\\"\u003c/code\u003e in \u003ccode\u003emethod_config\u003c/code\u003e). The default is \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.\u003c/p\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"The race is only reachable when `MPP.Methods.Tempo` is configured with a dedup store (`\\\"store\\\"` in `method_config`). The default is `nil`, which runs the library statelessly and provides no application-level replay protection at all, a documented property rather than part of this issue.\", \"base64\": false}]}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"0.6.1\", \"versionStartIncluding\": \"0.2.0\"}], \"operator\": \"OR\"}], \"operator\": \"AND\"}], \"providerMetadata\": {\"orgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"shortName\": \"EEF\", \"dateUpdated\": \"2026-08-19T17:19:43.696Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-73829\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-19T18:58:33.322Z\", \"dateReserved\": \"2026-08-17T11:15:02.320Z\", \"assignerOrgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"datePublished\": \"2026-08-19T17:19:43.696Z\", \"assignerShortName\": \"EEF\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.