CVE-2026-82750 (GCVE-0-2026-82750)

Vulnerability from cvelistv5 – Published: 2026-09-06 16:08 – Updated: 2026-09-08 18:25
VLAI
Title
Unbounded EIP-7702 authorization list in mpp Tempo fee-payer sponsorship inflates gas cost and sponsors account delegation
Summary
Improper Validation of Specified Quantity in Input in ZenHive mpp allows an unauthenticated remote client to inflate the fee-payer's gas cost per sponsored payment by a large multiplier and to have the sponsor pay for EIP-7702 account delegations of the client's choosing. When the server sponsors Tempo payments, MPP.Methods.Tempo.FeePayerPolicy.measure/3 in lib/mpp/methods/tempo/fee_payer_policy.ex bounds the gas fields, the fee budget, the validity window and the access list of the client-signed 0x76 envelope, but never reads its aa_authorization_list field. Every signed delegation in that list is charged as intrinsic gas before the payment call runs, so a client attaching delegations from throwaway authority keys makes the sponsor pay for them within the default gas_limit ceiling. At the reporter's default of seven entries the sponsored cost rises from about 46,575 gas to about 1,884,087 gas. Because each entry is applied as a persistent set-code delegation, a client can also upgrade its own accounts to delegated code at the sponsor's expense. This issue affects mpp: from 0.2.0 before 0.16.1.
Severity
8.3 (High)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-08 18:25 UTC
CWE
  • CWE-1284 - Improper Validation of Specified Quantity in Input
Assigner
EEF CNA under the mitre root
CNA scorecard A 97/100 over 357 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
ZenHive mpp Affected: 0.2.0 , < 0.16.1 (semver)
    cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*
Create a notification for this product.
ZenHive mpp Affected: d29d54e507918db00a5b65d90136b73166c017d7 , < 0482572b47e1ffe1537ab80ab613d47b92833c2d (git)
    cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*
Create a notification for this product.
Credits
Kian Kai Ang Kian Kai Ang E.FU Jonatan Männchen / EEF
Show details on NVD website
To clipboard 

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    "dateReserved": "2026-08-31T01:00:09.774Z",
    "dateUpdated": "2026-09-08T18:25:42.388Z",
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            "value": "Improper Validation of Specified Quantity in Input in ZenHive mpp allows an unauthenticated remote client to inflate the fee-payer\u0027s gas cost per sponsored payment by a large multiplier and to have the sponsor pay for EIP-7702 account delegations of the client\u0027s choosing.\n\nWhen the server sponsors Tempo payments, MPP.Methods.Tempo.FeePayerPolicy.measure/3 in lib/mpp/methods/tempo/fee_payer_policy.ex bounds the gas fields, the fee budget, the validity window and the access list of the client-signed 0x76 envelope, but never reads its aa_authorization_list field. Every signed delegation in that list is charged as intrinsic gas before the payment call runs, so a client attaching delegations from throwaway authority keys makes the sponsor pay for them within the default gas_limit ceiling. At the reporter\u0027s default of seven entries the sponsored cost rises from about 46,575 gas to about 1,884,087 gas. Because each entry is applied as a persistent set-code delegation, a client can also upgrade its own accounts to delegated code at the sponsor\u0027s expense.\n\nThis issue affects mpp: from 0.2.0 before 0.16.1."
          }
        ],
        "id": "CVE-2026-82750",
        "lastModified": "2026-09-08T19:20:01.200",
        "metrics": {
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                "modifiedAttackVector": "NOT_DEFINED",
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                "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/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",
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        "references": [
          {
            "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "url": "https://cna.erlef.org/cves/CVE-2026-82750.html"
          },
          {
            "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "url": "https://github.com/ZenHive/mpp/commit/0482572b47e1ffe1537ab80ab613d47b92833c2d"
          },
          {
            "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "url": "https://github.com/ZenHive/mpp/security/advisories/GHSA-5qrp-r24c-w6jr"
          },
          {
            "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "url": "https://osv.dev/vulnerability/EEF-CVE-2026-82750"
          }
        ],
        "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "vulnStatus": "Deferred",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-1284"
              }
            ],
            "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "type": "Secondary"
          }
        ]
      }
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2026-82750",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-09-08T18:25:27.116993Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-09-08T18:25:34.241Z",
              "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": [
                "\u0027Elixir.MPP.Methods.Tempo.FeePayerPolicy\u0027",
                "\u0027Elixir.MPP.Methods.Tempo\u0027"
              ],
              "packageName": "mpp",
              "packageURL": "pkg:hex/mpp",
              "product": "mpp",
              "programFiles": [
                "lib/mpp/methods/tempo/fee_payer_policy.ex",
                "lib/mpp/methods/tempo.ex"
              ],
              "programRoutines": [
                {
                  "name": "\u0027Elixir.MPP.Methods.Tempo.FeePayerPolicy\u0027:measure/3"
                },
                {
                  "name": "\u0027Elixir.MPP.Methods.Tempo.FeePayerPolicy\u0027:validate/3"
                },
                {
                  "name": "\u0027Elixir.MPP.Methods.Tempo\u0027:verify/2"
                }
              ],
              "repo": "https://github.com/ZenHive/mpp",
              "vendor": "ZenHive",
              "versions": [
                {
                  "lessThan": "0.16.1",
                  "status": "affected",
                  "version": "0.2.0",
                  "versionType": "semver"
                }
              ]
            },
            {
              "collectionURL": "https://github.com",
              "cpes": [
                "cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"
              ],
              "defaultStatus": "unaffected",
              "modules": [
                "\u0027Elixir.MPP.Methods.Tempo.FeePayerPolicy\u0027",
                "\u0027Elixir.MPP.Methods.Tempo\u0027"
              ],
              "packageName": "zenhive/mpp",
              "packageURL": "pkg:github/zenhive/mpp",
              "product": "mpp",
              "programFiles": [
                "lib/mpp/methods/tempo/fee_payer_policy.ex",
                "lib/mpp/methods/tempo.ex"
              ],
              "programRoutines": [
                {
                  "name": "\u0027Elixir.MPP.Methods.Tempo.FeePayerPolicy\u0027:measure/3"
                },
                {
                  "name": "\u0027Elixir.MPP.Methods.Tempo.FeePayerPolicy\u0027:validate/3"
                },
                {
                  "name": "\u0027Elixir.MPP.Methods.Tempo\u0027:verify/2"
                }
              ],
              "repo": "https://github.com/ZenHive/mpp",
              "vendor": "ZenHive",
              "versions": [
                {
                  "lessThan": "0482572b47e1ffe1537ab80ab613d47b92833c2d",
                  "status": "affected",
                  "version": "d29d54e507918db00a5b65d90136b73166c017d7",
                  "versionType": "git"
                }
              ]
            }
          ],
          "configurations": [
            {
              "lang": "en",
              "supportingMedia": [
                {
                  "base64": false,
                  "type": "text/html",
                  "value": "\u003cp\u003eOnly deployments that enable Tempo server-side fee sponsorship are affected, through \u003ccode\u003e\"fee_payer\" =\u0026gt; true\u003c/code\u003e in \u003ccode\u003emethod_config\u003c/code\u003e with either local co-signing (\u003ccode\u003efee_payer_private_key\u003c/code\u003e) or hosted sponsorship (\u003ccode\u003efee_payer_url\u003c/code\u003e). Sponsorship is disabled by default.\u003c/p\u003e"
                },
                {
                  "base64": false,
                  "type": "text/markdown",
                  "value": "Only deployments that enable Tempo server-side fee sponsorship are affected, through `\"fee_payer\" =\u003e true` in `method_config` with either local co-signing (`fee_payer_private_key`) or hosted sponsorship (`fee_payer_url`). Sponsorship is disabled by default."
                }
              ],
              "value": "Only deployments that enable Tempo server-side fee sponsorship are affected, through \"fee_payer\" =\u003e true in method_config with either local co-signing (fee_payer_private_key) or hosted sponsorship (fee_payer_url). Sponsorship is disabled by default."
            }
          ],
          "cpeApplicability": [
            {
              "nodes": [
                {
                  "cpeMatch": [
                    {
                      "criteria": "cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "0.16.1",
                      "versionStartIncluding": "0.2.0",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ],
              "operator": "AND"
            }
          ],
          "credits": [
            {
              "lang": "en",
              "type": "finder",
              "value": "Kian Kai Ang"
            },
            {
              "lang": "en",
              "type": "reporter",
              "value": "Kian Kai Ang"
            },
            {
              "lang": "en",
              "type": "remediation developer",
              "value": "E.FU"
            },
            {
              "lang": "en",
              "type": "coordinator",
              "value": "Jonatan M\u00e4nnchen / EEF"
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "supportingMedia": [
                {
                  "base64": false,
                  "type": "text/html",
                  "value": "\u003cp\u003eImproper Validation of Specified Quantity in Input in ZenHive mpp allows an unauthenticated remote client to inflate the fee-payer\u0027s gas cost per sponsored payment by a large multiplier and to have the sponsor pay for EIP-7702 account delegations of the client\u0027s choosing.\u003c/p\u003e\n\u003cp\u003eWhen the server sponsors Tempo payments, \u003ccode\u003eMPP.Methods.Tempo.FeePayerPolicy.measure/3\u003c/code\u003e in \u003ccode\u003elib/mpp/methods/tempo/fee_payer_policy.ex\u003c/code\u003e bounds the gas fields, the fee budget, the validity window and the access list of the client-signed \u003ccode\u003e0x76\u003c/code\u003e envelope, but never reads its \u003ccode\u003eaa_authorization_list\u003c/code\u003e field. Every signed delegation in that list is charged as intrinsic gas before the payment call runs, so a client attaching delegations from throwaway authority keys makes the sponsor pay for them within the default \u003ccode\u003egas_limit\u003c/code\u003e ceiling. At the reporter\u0027s default of seven entries the sponsored cost rises from about 46,575 gas to about 1,884,087 gas. Because each entry is applied as a persistent set-code delegation, a client can also upgrade its own accounts to delegated code at the sponsor\u0027s expense.\u003c/p\u003e\n\u003cp\u003eThis issue affects mpp: from 0.2.0 before 0.16.1.\u003c/p\u003e"
                },
                {
                  "base64": false,
                  "type": "text/markdown",
                  "value": "Improper Validation of Specified Quantity in Input in ZenHive mpp allows an unauthenticated remote client to inflate the fee-payer\u0027s gas cost per sponsored payment by a large multiplier and to have the sponsor pay for EIP-7702 account delegations of the client\u0027s choosing.\n\nWhen the server sponsors Tempo payments, `MPP.Methods.Tempo.FeePayerPolicy.measure/3` in `lib/mpp/methods/tempo/fee_payer_policy.ex` bounds the gas fields, the fee budget, the validity window and the access list of the client-signed `0x76` envelope, but never reads its `aa_authorization_list` field. Every signed delegation in that list is charged as intrinsic gas before the payment call runs, so a client attaching delegations from throwaway authority keys makes the sponsor pay for them within the default `gas_limit` ceiling. At the reporter\u0027s default of seven entries the sponsored cost rises from about 46,575 gas to about 1,884,087 gas. Because each entry is applied as a persistent set-code delegation, a client can also upgrade its own accounts to delegated code at the sponsor\u0027s expense.\n\nThis issue affects mpp: from 0.2.0 before 0.16.1."
                }
              ],
              "value": "Improper Validation of Specified Quantity in Input in ZenHive mpp allows an unauthenticated remote client to inflate the fee-payer\u0027s gas cost per sponsored payment by a large multiplier and to have the sponsor pay for EIP-7702 account delegations of the client\u0027s choosing.\n\nWhen the server sponsors Tempo payments, MPP.Methods.Tempo.FeePayerPolicy.measure/3 in lib/mpp/methods/tempo/fee_payer_policy.ex bounds the gas fields, the fee budget, the validity window and the access list of the client-signed 0x76 envelope, but never reads its aa_authorization_list field. Every signed delegation in that list is charged as intrinsic gas before the payment call runs, so a client attaching delegations from throwaway authority keys makes the sponsor pay for them within the default gas_limit ceiling. At the reporter\u0027s default of seven entries the sponsored cost rises from about 46,575 gas to about 1,884,087 gas. Because each entry is applied as a persistent set-code delegation, a client can also upgrade its own accounts to delegated code at the sponsor\u0027s expense.\n\nThis issue affects mpp: from 0.2.0 before 0.16.1."
            }
          ],
          "impacts": [
            {
              "capecId": "CAPEC-130",
              "descriptions": [
                {
                  "lang": "en",
                  "value": "CAPEC-130 Excessive Allocation"
                }
              ]
            }
          ],
          "metrics": [
            {
              "cvssV4_0": {
                "Automatable": "NOT_DEFINED",
                "Recovery": "NOT_DEFINED",
                "Safety": "NOT_DEFINED",
                "attackComplexity": "LOW",
                "attackRequirements": "PRESENT",
                "attackVector": "NETWORK",
                "baseScore": 8.3,
                "baseSeverity": "HIGH",
                "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:H/VA:L/SC:N/SI:N/SA:N",
                "version": "4.0",
                "vulnAvailabilityImpact": "LOW",
                "vulnConfidentialityImpact": "NONE",
                "vulnIntegrityImpact": "HIGH",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
              },
              "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": {
            "dateUpdated": "2026-09-06T16:08:41.089Z",
            "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
            "shortName": "EEF"
          },
          "references": [
            {
              "tags": [
                "vendor-advisory",
                "related"
              ],
              "url": "https://github.com/ZenHive/mpp/security/advisories/GHSA-5qrp-r24c-w6jr"
            },
            {
              "tags": [
                "related"
              ],
              "url": "https://cna.erlef.org/cves/CVE-2026-82750.html"
            },
            {
              "tags": [
                "related"
              ],
              "url": "https://osv.dev/vulnerability/EEF-CVE-2026-82750"
            },
            {
              "tags": [
                "patch"
              ],
              "url": "https://github.com/ZenHive/mpp/commit/0482572b47e1ffe1537ab80ab613d47b92833c2d"
            }
          ],
          "source": {
            "discovery": "EXTERNAL"
          },
          "title": "Unbounded EIP-7702 authorization list in mpp Tempo fee-payer sponsorship inflates gas cost and sponsors account delegation",
          "workarounds": [
            {
              "lang": "en",
              "supportingMedia": [
                {
                  "base64": false,
                  "type": "text/html",
                  "value": "\u003cp\u003eDisable Tempo fee sponsorship by leaving \u003ccode\u003e\"fee_payer\"\u003c/code\u003e at its default of \u003ccode\u003efalse\u003c/code\u003e and setting no \u003ccode\u003efee_payer_url\u003c/code\u003e, so the client pays its own gas. Where sponsorship must stay enabled, lower the \u003ccode\u003emax_gas\u003c/code\u003e override in \u003ccode\u003efee_payer_policy\u003c/code\u003e to just above what a legitimate sponsored payment needs (a TIP-20 transfer is roughly 50,000 gas), so an envelope padded with delegations either fails the policy or runs out of gas at a bounded cost. This bounds the inflation without closing it.\u003c/p\u003e"
                },
                {
                  "base64": false,
                  "type": "text/markdown",
                  "value": "Disable Tempo fee sponsorship by leaving `\"fee_payer\"` at its default of `false` and setting no `fee_payer_url`, so the client pays its own gas. Where sponsorship must stay enabled, lower the `max_gas` override in `fee_payer_policy` to just above what a legitimate sponsored payment needs (a TIP-20 transfer is roughly 50,000 gas), so an envelope padded with delegations either fails the policy or runs out of gas at a bounded cost. This bounds the inflation without closing it."
                }
              ],
              "value": "Disable Tempo fee sponsorship by leaving \"fee_payer\" at its default of false and setting no fee_payer_url, so the client pays its own gas. Where sponsorship must stay enabled, lower the max_gas override in fee_payer_policy to just above what a legitimate sponsored payment needs (a TIP-20 transfer is roughly 50,000 gas), so an envelope padded with delegations either fails the policy or runs out of gas at a bounded cost. This bounds the inflation without closing it."
            }
          ]
        }
      },
      "cveMetadata": {
        "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "assignerShortName": "EEF",
        "cveId": "CVE-2026-82750",
        "datePublished": "2026-09-06T16:08:41.089Z",
        "dateReserved": "2026-08-31T01:00:09.774Z",
        "dateUpdated": "2026-09-08T18:25:42.388Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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