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.
" } ], "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" } ], "descriptions": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "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.
When 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.
This issue affects mpp: from 0.2.0 before 0.6.0.
" } ], "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." } ], "impacts": [ { "capecId": "CAPEC-130", "descriptions": [ { "lang": "en", "value": "CAPEC-130 Excessive Allocation" } ] } ], "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": { "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-07-18T04:12:26.916Z" }, "references": [ { "tags": [ "vendor-advisory", "related" ], "url": "https://github.com/ZenHive/mpp/security/advisories/GHSA-vv77-66rf-pm86" }, { "tags": [ "related" ], "url": "https://cna.erlef.org/cves/CVE-2026-59695.html" }, { "tags": [ "related" ], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-59695" }, { "tags": [ "patch" ], "url": "https://github.com/ZenHive/mpp/commit/5d6338e2334084c5f2a78cfcca474830733ed7e8" } ], "source": { "discovery": "EXTERNAL" }, "title": "Unbounded max_fee_per_gas in mpp Tempo fee-payer enables single-request wallet drain", "x_generator": { "engine": "cvelib 1.8.0" } }, "adp": [ { "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" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-07-17T12:53:17.645Z" } } ] } }