{"id":"CVE-2026-59695","state":"PUBLISHED","title":"Unbounded max_fee_per_gas in mpp Tempo fee-payer enables single-request wallet drain","description":"Improper Validation of Specified Quantity in Input in ZenHive mpp allows an unauthenticated remote client to drain the fee-payer wallet in a single request by naming an arbitrarily high gas price.\n\nWhen the mpp Elixir library is configured as fee payer (fee_payer: true), MPP.Tempo.Transaction.cosign_fee_payer/3 re-signs the client-supplied base fields of the 0x76 AASigned envelope verbatim, including max_fee_per_gas and max_priority_fee_per_gas, without validating that they are within reasonable bounds. A malicious client embeds arbitrarily large values for these fields in the signed envelope. The server co-signs and broadcasts the transaction. The effective_gas_price billed against the fee-payer wallet is derived from the attacker-supplied ceilings, so the server pays those inflated per-gas rates out of its own wallet. A single crafted request can drain the wallet entirely, after which the server can no longer sponsor gas for legitimate payment requests.\n\nThis issue affects mpp: from 0.2.0 before 0.6.0.","publishedAt":"2026-07-17T10:11:43.674Z","updatedAt":"2026-07-18T04:12:26.916Z","severity":{"score":8.3,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N","source":"EEF"},"assigner":"EEF","products":["ZenHive mpp"],"affected":[{"vendor":"ZenHive","product":"mpp","packageName":"mpp","packageURL":"pkg:hex/mpp","defaultStatus":"unaffected","versions":[{"version":"0.2.0","status":"affected","lessThan":"0.6.0","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"],"modules":["'Elixir.MPP.Tempo.Transaction'"],"programFiles":["lib/mpp/tempo/transaction.ex"],"programRoutines":[{"name":"'Elixir.MPP.Tempo.Transaction':cosign_fee_payer/3"}],"repo":"https://github.com/ZenHive/mpp"},{"vendor":"ZenHive","product":"mpp","packageName":"ZenHive/mpp","packageURL":"pkg:github/ZenHive/mpp","defaultStatus":"unaffected","versions":[{"version":"d29d54e507918db00a5b65d90136b73166c017d7","status":"affected","lessThan":"5d6338e2334084c5f2a78cfcca474830733ed7e8","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"],"modules":["'Elixir.MPP.Tempo.Transaction'"],"programFiles":["lib/mpp/tempo/transaction.ex"],"programRoutines":[{"name":"'Elixir.MPP.Tempo.Transaction':cosign_fee_payer/3"}],"repo":"https://github.com/ZenHive/mpp"}],"references":["https://github.com/ZenHive/mpp/security/advisories/GHSA-vv77-66rf-pm86","https://cna.erlef.org/cves/CVE-2026-59695.html","https://osv.dev/vulnerability/EEF-CVE-2026-59695","https://github.com/ZenHive/mpp/commit/5d6338e2334084c5f2a78cfcca474830733ed7e8"],"weaknesses":["CWE-1284"],"ingestedAt":"2026-10-29T20:12:32.778Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/59xxx/CVE-2026-59695.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-59695","state":"PUBLISHED","datePublished":"2026-07-17T10:11:43.674Z","dateUpdated":"2026-07-18T04:12:26.916Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-07-06T14:05:47.003Z"},"containers":{"cna":{"title":"Unbounded max_fee_per_gas in mpp Tempo fee-payer enables single-request wallet drain","descriptions":[{"lang":"en","value":"Improper Validation of Specified Quantity in Input in ZenHive mpp allows an unauthenticated remote client to drain the fee-payer wallet in a single request by naming an arbitrarily high gas price.\n\nWhen the mpp Elixir library is configured as fee payer (fee_payer: true), MPP.Tempo.Transaction.cosign_fee_payer/3 re-signs the client-supplied base fields of the 0x76 AASigned envelope verbatim, including max_fee_per_gas and max_priority_fee_per_gas, without validating that they are within reasonable bounds. A malicious client embeds arbitrarily large values for these fields in the signed envelope. The server co-signs and broadcasts the transaction. The effective_gas_price billed against the fee-payer wallet is derived from the attacker-supplied ceilings, so the server pays those inflated per-gas rates out of its own wallet. A single crafted request can drain the wallet entirely, after which the server can no longer sponsor gas for legitimate payment requests.\n\nThis issue affects mpp: from 0.2.0 before 0.6.0."}],"affected":[{"vendor":"ZenHive","product":"mpp","packageName":"mpp","packageURL":"pkg:hex/mpp","defaultStatus":"unaffected","versions":[{"version":"0.2.0","status":"affected","lessThan":"0.6.0","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"],"modules":["'Elixir.MPP.Tempo.Transaction'"],"programFiles":["lib/mpp/tempo/transaction.ex"],"programRoutines":[{"name":"'Elixir.MPP.Tempo.Transaction':cosign_fee_payer/3"}],"repo":"https://github.com/ZenHive/mpp"},{"vendor":"ZenHive","product":"mpp","packageName":"ZenHive/mpp","packageURL":"pkg:github/ZenHive/mpp","defaultStatus":"unaffected","versions":[{"version":"d29d54e507918db00a5b65d90136b73166c017d7","status":"affected","lessThan":"5d6338e2334084c5f2a78cfcca474830733ed7e8","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"],"modules":["'Elixir.MPP.Tempo.Transaction'"],"programFiles":["lib/mpp/tempo/transaction.ex"],"programRoutines":[{"name":"'Elixir.MPP.Tempo.Transaction':cosign_fee_payer/3"}],"repo":"https://github.com/ZenHive/mpp"}],"references":[{"url":"https://github.com/ZenHive/mpp/security/advisories/GHSA-vv77-66rf-pm86","tags":["vendor-advisory","related"]},{"url":"https://cna.erlef.org/cves/CVE-2026-59695.html","tags":["related"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-59695","tags":["related"]},{"url":"https://github.com/ZenHive/mpp/commit/5d6338e2334084c5f2a78cfcca474830733ed7e8","tags":["patch"]}],"metrics":[{"cvssV4_0":{"attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":8.3,"baseSeverity":"HIGH","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-1284","description":"CWE-1284 Improper Validation of Specified Quantity in Input","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-07-18T04:12:26.916Z"},"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>The vulnerable code path is only reachable when the <tt>MPP.Methods.Tempo</tt> method is configured with <tt>fee_payer: true</tt> (server-side gas sponsorship). Default deployments with <tt>fee_payer: false</tt> are not affected, since the client pays for gas out of its own wallet.</p>"}],"value":"The vulnerable code path is only reachable when the MPP.Methods.Tempo method is configured with fee_payer: true (server-side gas sponsorship). Default deployments with fee_payer: false are not affected, since the client pays for gas out of its own wallet."}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*","versionEndExcluding":"0.6.0","versionStartIncluding":"0.2.0","vulnerable":true}],"negate":false,"operator":"AND"}],"operator":"OR"}],"credits":[{"lang":"en","type":"finder","value":"Kian Kai Ang"},{"lang":"en","type":"remediation developer","value":"E.FU"},{"lang":"en","type":"analyst","value":"Jonatan Männchen / EEF"}],"impacts":[{"capecId":"CAPEC-130","descriptions":[{"lang":"en","value":"CAPEC-130 Excessive Allocation"}]}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/ZenHive/mpp/security/advisories/GHSA-vv77-66rf-pm86","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-17T12:53:10.647332Z","id":"CVE-2026-59695","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-17T12:53:17.645Z"}}]}}}