{"id":"CVE-2026-59695","aliases":["EEF-CVE-2026-59695","EUVD-2026-45158","GHSA-6v7f-h3qg-wwpp","GHSA-vv77-66rf-pm86"],"status":"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.","severity":{"version":"4.0","score":8.3,"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","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00382,"percentile":0.32764,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1284","CWE-20"],"published":"2026-07-17T10:11:43Z","modified":"2026-10-28T02:30:47Z","fixes":[{"ecosystem":"Hex","package":"mpp","fixed_in":["0.6.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Hex","package":"mpp","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.2.0"},{"fixed":"0.6.0"}]}]},{"source":"osv","ecosystem":"Hex","package":"mpp","ranges":[{"type":"SEMVER","events":[{"introduced":"0.2.0"},{"fixed":"0.6.0"}]}],"versions":["0.2.0","0.3.0","0.3.1","0.3.2","0.4.0"]},{"source":"osv","ecosystem":"Hex","package":"mpp","ranges":[{"type":"SEMVER","events":[{"introduced":"0.2.0"},{"fixed":"0.6.0"}]}],"versions":["0.2.0","0.3.0","0.3.1","0.3.2","0.4.0"]}],"products":[{"vendor":"zenhive","product":"mpp"}],"references":[{"url":"https://github.com/ZenHive/mpp/security/advisories/GHSA-vv77-66rf-pm86","tags":["vendor-advisory","related","exploit","advisory","web"]},{"url":"https://cna.erlef.org/cves/CVE-2026-59695.html","tags":["related","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-59695","tags":["related","web"]},{"url":"https://github.com/ZenHive/mpp/commit/5d6338e2334084c5f2a78cfcca474830733ed7e8","tags":["patch","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59695","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-6v7f-h3qg-wwpp"},{"url":"https://github.com/ZenHive/mpp/releases/tag/v0.6.0","tags":["web"]},{"url":"https://github.com/advisories/GHSA-vv77-66rf-pm86"},{"url":"https://github.com","tags":["web"]},{"url":"https://repo.hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59695.json","tags":["advisory"]},{"url":"https://github.com/ZenHive/mpp","tags":["package"]},{"url":"https://hex.pm/packages/mpp","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-59695","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.","status":"published","published":"2026-07-17T10:11:43.674Z","modified":"2026-07-18T04:12:26.916Z","cvss":[{"version":"4.0","score":8.3,"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","level":"high","assessor":"cna"}],"cwes":["CWE-1284"],"updated_at":"2026-11-02T14:19:58.560602Z"}],"euvd":[{"id":"EUVD-2026-45158","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.","status":"published","published":"2026-07-17T10:11:43Z","modified":"2026-07-18T04:12:26Z","cvss":[{"version":"4.0","score":8.3,"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","level":"high"}],"updated_at":"2026-11-02T18:19:50.065723Z"}],"ghsa":[{"id":"GHSA-6v7f-h3qg-wwpp","title":"Improper Validation of Specified Quantity in Input in ZenHive mpp allows an unauthenticated...","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.","status":"published","published":"2026-07-17T12:31:29Z","modified":"2026-07-17T12:31:30Z","cvss":[{"version":"4.0","score":8.3,"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/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","level":"high"}],"cwes":["CWE-1284"],"updated_at":"2026-11-02T15:09:35.141236Z"},{"id":"GHSA-vv77-66rf-pm86","title":"mpp vulnerable to Gas Draining with no limit","description":"### Details\nWhen the server acts as the fee_payer, the `mpp` Elixir 0.4.0 does not validate `gas_limit`, `max_fee_per_gas` and `max_priority_fee_per_gas` before cosigning the client's fee-payer transaction. A malicious client embeds arbitrarily large `max_fee_per_gas` and `max_priority_fee_per_gas` values in the signed envelope. The server cosigns and broadcasts — paying those inflated gas costs from its own wallet based on the `effective_gas_price` calculated from the high `max_fee_per_gas` and `max_priority_fee_per_gas` set by the client.\n\n**Vulnerable function:** `cosign_fee_payer/3` in [`transaction.ex`](https://hex.pm/packages/mpp/0.4.0) around lines 229–262.\n\n### PoC\nThe PoC is provided below. It is configured to reproduce the attack on Tempo Moderate testnet within a Docker environment. Download the PoC and run:\n```bash\nunzip mpp_elixir_PoC.zip\ncd mpp_elixir\ndocker build -t mpp-elixir-gasdrain .\ndocker run --rm mpp-elixir-gasdrain\n``` \nThere are more details in `mpp_elixir/README.md`\n\n### Impact\nBy draining the server's wallet, an attacker causes direct financial loss to the organization. Furthermore, if the server's funds are drained completely, legitimate clients will have their requests fail, as the server can no longer fund future transactions, effectively creating a Denial of Service (DoS) attack.","status":"published","published":"2026-09-25T21:44:12Z","modified":"2026-09-25T21:44:13Z","cvss":[{"version":"4.0","score":8.8,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T14:41:22.654187Z"}],"nvd":[{"id":"CVE-2026-59695","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.","status":"published","published":"2026-07-17T11:17:14.117Z","modified":"2026-10-24T20:10:00.137Z","cvss":[{"version":"4.0","score":8.3,"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/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","level":"high","assessor":"secondary"}],"cwes":["CWE-1284"],"updated_at":"2026-11-02T14:12:30.250437Z"}],"osv":[{"id":"CVE-2026-59695","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.","status":"published","published":"2026-07-17T10:11:43.674Z","modified":"2026-10-28T02:30:47.443910744Z","cvss":[{"version":"4.0","score":8.3,"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","level":"high"}],"cwes":["CWE-1284"],"updated_at":"2026-11-02T15:45:12.496548Z"},{"id":"EEF-CVE-2026-59695","title":"Unbounded max_fee_per_gas in mpp Tempo fee-payer enables single-request wallet drain","description":"## Summary\n\nImproper 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.\n\n## Configurations\n\nThe 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.","status":"published","published":"2026-07-17T10:11:43.674Z","modified":"2026-09-08T03:45:09.283445419Z","cvss":[{"version":"4.0","score":8.3,"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","level":"high"}],"cwes":["CWE-1284"],"updated_at":"2026-11-02T15:46:33.520522Z"},{"id":"GHSA-vv77-66rf-pm86","title":"mpp vulnerable to Gas Draining with no limit","description":"### Details\nWhen the server acts as the fee_payer, the `mpp` Elixir 0.4.0 does not validate `gas_limit`, `max_fee_per_gas` and `max_priority_fee_per_gas` before cosigning the client's fee-payer transaction. A malicious client embeds arbitrarily large `max_fee_per_gas` and `max_priority_fee_per_gas` values in the signed envelope. The server cosigns and broadcasts — paying those inflated gas costs from its own wallet based on the `effective_gas_price` calculated from the high `max_fee_per_gas` and `max_priority_fee_per_gas` set by the client.\n\n**Vulnerable function:** `cosign_fee_payer/3` in [`transaction.ex`](https://hex.pm/packages/mpp/0.4.0) around lines 229–262.\n\n### PoC\nThe PoC is provided below. It is configured to reproduce the attack on Tempo Moderate testnet within a Docker environment. Download the PoC and run:\n```bash\nunzip mpp_elixir_PoC.zip\ncd mpp_elixir\ndocker build -t mpp-elixir-gasdrain .\ndocker run --rm mpp-elixir-gasdrain\n``` \nThere are more details in `mpp_elixir/README.md`\n\n### Impact\nBy draining the server's wallet, an attacker causes direct financial loss to the organization. Furthermore, if the server's funds are drained completely, legitimate clients will have their requests fail, as the server can no longer fund future transactions, effectively creating a Denial of Service (DoS) attack.","status":"published","published":"2026-09-25T21:44:12Z","modified":"2026-09-25T23:00:09.850205107Z","cvss":[{"version":"4.0","score":8.8,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T15:46:57.694388Z"}]}}