{"id":"CVE-2026-82750","summary":"Unbounded EIP-7702 authorization list in mpp Tempo fee-payer sponsorship inflates gas cost and sponsors account delegation","details":"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.\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'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.\n\nThis issue affects mpp: from 0.2.0 before 0.16.1.","aliases":["EEF-CVE-2026-82750","GHSA-5qrp-r24c-w6jr"],"modified":"2026-09-10T03:30:51.512503608Z","published":"2026-09-06T16:08:41.089Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82750.json","unresolved_ranges":[{"extracted_events":[{"introduced":"0.2.0"},{"fixed":"0.16.1"},{"introduced":"d29d54e507918db00a5b65d90136b73166c017d7"},{"fixed":"0482572b47e1ffe1537ab80ab613d47b92833c2d"}],"source":"AFFECTED_FIELD"},{"extracted_events":[{"introduced":"0.2.0"},{"fixed":"0.16.1"}],"source":"CPE_FIELD"},{"source":"DESCRIPTION","extracted_events":[{"introduced":"0.2.0"},{"fixed":"0.16.1"}]}],"cna_assigner":"EEF","cwe_ids":["CWE-1284"]},"references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-82750.html"},{"type":"WEB","url":"https://github.com"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-82750"},{"type":"WEB","url":"https://repo.hex.pm"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82750.json"},{"type":"ADVISORY","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":"FIX","url":"https://github.com/ZenHive/mpp/commit/0482572b47e1ffe1537ab80ab613d47b92833c2d"},{"type":"PACKAGE","url":"https://github.com/ZenHive/mpp"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zenhive/mpp","events":[{"introduced":"0"},{"fixed":"0482572b47e1ffe1537ab80ab613d47b92833c2d"}],"database_specific":{"source":"REFERENCES"}}],"versions":["v0.16.0","v0.15.0","v0.14.0","v0.13.0","v0.12.0","v0.11.0","v0.10.0","v0.9.0","v0.8.0","v0.7.0","v0.6.4","v0.6.3","v0.6.1","v0.6.0","v0.5.1","v0.4.0","v0.3.0","v0.2.0","v0.1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-82750.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","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"}]}