{"api_version":"1","generated_at":"2026-08-22T19:55:35+00:00","cve":"CVE-2026-73829","urls":{"html":"https://cve.report/CVE-2026-73829","api":"https://cve.report/api/cve/CVE-2026-73829.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-73829","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-73829"},"summary":{"title":"Non-atomic hash-credential dedup in mpp Tempo allows replay of a confirmed payment under a concurrent race","description":"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.","state":"PUBLISHED","assigner":"EEF","published_at":"2026-08-19 18:17:25","updated_at":"2026-08-20 13:02:12"},"problem_types":["CWE-367","CWE-367 CWE-367 Time-of-check Time-of-use (TOCTOU) Race 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Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73829","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"ZenHive","product":"mpp","version":"affected 0.2.0 0.6.1 semver","platforms":[]},{"source":"CNA","vendor":"ZenHive","product":"mpp","version":"affected f8904666061fbab695874856d8fcd02c471dfe1b 46c5b0e1311da7d92190dc7d9ea89027a1d365e9 git","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[{"source":"CNA","value":"Jonatan Männchen / EEF","lang":"en"},{"source":"CNA","value":"E.FU","lang":"en"},{"source":"CNA","value":"E.FU","lang":"en"}],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"73829","cve":"CVE-2026-73829","epss":"0.002400000","percentile":"0.154530000","score_date":"2026-08-21","updated_at":"2026-08-22 00:12:50"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2026-73829","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","timestamp":"2026-08-19T18:55:14.304500Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2026-08-19T18:58:33.322Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.MPP.Methods.Tempo'"],"packageName":"mpp","packageURL":"pkg:hex/mpp","product":"mpp","programFiles":["lib/mpp/methods/tempo.ex"],"programRoutines":[{"name":"'Elixir.MPP.Methods.Tempo':verify/2"}],"repo":"https://github.com/ZenHive/mpp","vendor":"ZenHive","versions":[{"lessThan":"0.6.1","status":"affected","version":"0.2.0","versionType":"semver"}]},{"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.MPP.Methods.Tempo'"],"packageName":"zenhive/mpp","packageURL":"pkg:github/zenhive/mpp","product":"mpp","programFiles":["lib/mpp/methods/tempo.ex"],"programRoutines":[{"name":"'Elixir.MPP.Methods.Tempo':verify/2"}],"repo":"https://github.com/ZenHive/mpp","vendor":"ZenHive","versions":[{"lessThan":"46c5b0e1311da7d92190dc7d9ea89027a1d365e9","status":"affected","version":"f8904666061fbab695874856d8fcd02c471dfe1b","versionType":"git"}]}],"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>The race is only reachable when <code>MPP.Methods.Tempo</code> is configured with a dedup store (<code>\"store\"</code> in <code>method_config</code>). The default is <code>nil</code>, which runs the library statelessly and provides no application-level replay protection at all, a documented property rather than part of this issue.</p>"},{"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."}],"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."}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*","versionEndExcluding":"0.6.1","versionStartIncluding":"0.2.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"analyst","value":"Jonatan Männchen / EEF"},{"lang":"en","type":"finder","value":"E.FU"},{"lang":"en","type":"remediation developer","value":"E.FU"}],"datePublic":"2026-06-29T00:00:00.000Z","descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>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.</p>\n<p>The <code>type=\"hash\"</code> credential path in <code>MPP.Methods.Tempo.verify/2</code> guards against replay with a non-atomic check-then-mark sequence: <code>check_hash_unused/2</code> reads the dedup store, an <code>eth_getTransactionReceipt</code> round trip verifies the payment on chain, and only then does <code>mark_hash_used/2</code> 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 <code>check_and_mark/2</code> primitive is available and used by the <code>type=\"transaction\"</code> path, but the hash path calls plain <code>get</code> and <code>put</code> even when the configured store implements it. Exploitation requires a dedup store to be configured; the default <code>nil</code> store is stateless and documented as offering no replay protection at all.</p>\n<p>This issue affects mpp: from 0.2.0 before 0.6.1.</p>"},{"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'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."}],"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'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."}],"impacts":[{"capecId":"CAPEC-29","descriptions":[{"lang":"en","value":"CAPEC-29 Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions"}]}],"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","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-367","description":"CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-08-19T17:19:43.696Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"references":[{"tags":["vendor-advisory","related"],"url":"https://github.com/ZenHive/mpp/security/advisories/GHSA-w8j7-7qc3-5f24"},{"tags":["related"],"url":"https://cna.erlef.org/cves/CVE-2026-73829.html"},{"tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-73829"},{"tags":["patch"],"url":"https://github.com/ZenHive/mpp/commit/46c5b0e1311da7d92190dc7d9ea89027a1d365e9"}],"source":{"discovery":"EXTERNAL"},"title":"Non-atomic hash-credential dedup in mpp Tempo allows replay of a confirmed payment under a concurrent race"}},"cveMetadata":{"assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","assignerShortName":"EEF","cveId":"CVE-2026-73829","datePublished":"2026-08-19T17:19:43.696Z","dateReserved":"2026-08-17T11:15:02.320Z","dateUpdated":"2026-08-19T18:58:33.322Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-19 18:17:25","lastModifiedDate":"2026-08-20 13:02:12","problem_types":["CWE-367","CWE-367 CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition"],"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"}}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-08-19T18:55:14.304500Z","id":"CVE-2026-73829","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"73829","Ordinal":"1","Title":"Non-atomic hash-credential dedup in mpp Tempo allows replay of a","CVE":"CVE-2026-73829","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"73829","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"Non-atomic hash-credential dedup in mpp Tempo allows replay of a"}]}}}