# CVE-2026-82750

## Summary

- **CVE ID:** CVE-2026-82750
- **Severity:** HIGH
- **CVSS Score:** 8.3 (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)
- **CWE:** CWE-1284
- **Published:** Sep 6, 2026
- **Last Modified:** Sep 8, 2026

## Description

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.

## Affected Products

- ZenHive — mpp (0.2.0)
- ZenHive — mpp (d29d54e507918db00a5b65d90136b73166c017d7)

## References

- [CNA](https://github.com/ZenHive/mpp/security/advisories/GHSA-5qrp-r24c-w6jr)
- [CNA](https://cna.erlef.org/cves/CVE-2026-82750.html)
- [CNA](https://osv.dev/vulnerability/EEF-CVE-2026-82750)
- [CNA](https://github.com/ZenHive/mpp/commit/0482572b47e1ffe1537ab80ab613d47b92833c2d)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.33%
- **EPSS Percentile:** 25.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._