CVE-2026-73541

Tempo fee sponsorship in mpp bounds each transaction but not aggregate exposure, allowing concurrent sponsor-wallet drain

Published Aug 19, 2026 CVSS 4.0 · 8.3 High EPSS < 1% KEV · Not listed
Description
Allocation of Resources Without Limits or Throttling in ZenHive mpp allows an unauthenticated remote client to drain the fee-payer wallet through concurrent sponsored payments, denying service to legitimate payers once it is empty.

MPP.Methods.Tempo.FeePayerPolicy enforces its ceilings (max_gas, max_fee_per_gas, max_priority_fee_per_gas, the worst-case gas_limit * max_fee_per_gas <= max_total_fee budget cap, and a validity window) against one transaction at a time, and nothing accounts for exposure across concurrent requests. reserve_hash_atomic/2 is keyed on the transaction hash, so it prevents duplicate broadcast of the same signed transaction but not N distinct sponsored transactions carrying distinct expiring nonces. Committed sponsor exposure is therefore N times max_total_fee, bounded by nothing in the library, and the default 900 second validity window lets co-signed transactions stay broadcastable and uncounted for that entire period.

This issue affects mpp: from 0.2.0 before 0.12.0.

Remediation

Vendor Workaround

Disable Tempo fee sponsorship by setting "fee_payer" => false (the default), so the client pays its own gas and the sponsor wallet is never committed. Where sponsorship must stay enabled, lowering max_total_fee and max_validity_window_seconds reduces the exposure each concurrent request can commit and how long it stays outstanding, without bounding the aggregate.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Zenhive machine Payments Protocol
CPEs cpe:2.3:a:zenhive:machine_payments_protocol:*:*:*:*:*:elixir:*:*
Vendors & Products Zenhive machine Payments Protocol
Metrics cvssV3_1

{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H'}

Type Values Removed Values Added
First Time appeared Zenhive
Zenhive mpp
Vendors & Products Zenhive
Zenhive mpp
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Allocation of Resources Without Limits or Throttling in ZenHive mpp allows an unauthenticated remote client to drain the fee-payer wallet through concurrent sponsored payments, denying service to legitimate payers once it is empty. MPP.Methods.Tempo.FeePayerPolicy enforces its ceilings (max_gas, max_fee_per_gas, max_priority_fee_per_gas, the worst-case gas_limit * max_fee_per_gas <= max_total_fee budget cap, and a validity window) against one transaction at a time, and nothing accounts for exposure across concurrent requests. reserve_hash_atomic/2 is keyed on the transaction hash, so it prevents duplicate broadcast of the same signed transaction but not N distinct sponsored transactions carrying distinct expiring nonces. Committed sponsor exposure is therefore N times max_total_fee, bounded by nothing in the library, and the default 900 second validity window lets co-signed transactions stay broadcastable and uncounted for that entire period. This issue affects mpp: from 0.2.0 before 0.12.0.
Title Tempo fee sponsorship in mpp bounds each transaction but not aggregate exposure, allowing concurrent sponsor-wallet drain
First Time appeared Zenhive
Zenhive mpp
Weaknesses CWE-770
CPEs cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*
Vendors & Products Zenhive
Zenhive mpp
References
Metrics cvssV4_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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
EEF
Published
Updated
Aug 19, 2026, 6:47 PM
Reserved
Aug 18, 2026, 10:00 AM
Status
Analyzed
Published
Aug 19, 2026, 6:17 PM
Modified
Sep 10, 2026, 6:24 PM