GHSA-Q4F3-JF9F-788F
Vulnerability from github – Published: 2026-09-06 18:34 – Updated: 2026-09-06 18:34Improper 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.
{
"affected": [],
"aliases": [
"CVE-2026-82750"
],
"database_specific": {
"cwe_ids": [
"CWE-1284"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-06T17:17:55Z",
"severity": "HIGH"
},
"details": "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": "GHSA-q4f3-jf9f-788f",
"modified": "2026-09-06T18:34:38Z",
"published": "2026-09-06T18:34:38Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/ZenHive/mpp/security/advisories/GHSA-5qrp-r24c-w6jr"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-82750"
},
{
"type": "WEB",
"url": "https://github.com/ZenHive/mpp/commit/0482572b47e1ffe1537ab80ab613d47b92833c2d"
},
{
"type": "WEB",
"url": "https://cna.erlef.org/cves/CVE-2026-82750.html"
},
{
"type": "WEB",
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-82750"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "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",
"type": "CVSS_V4"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.