TI-2026-42570 Aliases CVE-2026-59694 GHSA-r4hx-mhrp-xf73

Unbounded access list in mpp Tempo fee-payer inflates gas cost per payment

HIGH 69CWE-1284Published 2026-07-17 · Updated 2026-07-18

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: Present
Impact type: —
Confidentiality · integrity · availability: None · High · Low
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

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 payment by a large multiplier, degrading the sponsor's operating margin. When the mpp Elixir library is configured as fee payer (fee_payer: true), MPP.Tempo.Transaction.cosign_fee_payer/3 re-signs the client-supplied base fields of the 0x76 AASigned envelope verbatim, including the EIP-2930 access list, without validating its length or contents. EIP-2930 access list entries incur intrinsic gas (~2,400 gas per address, plus 1,900 gas per storage key) charged before any opcode executes, regardless of whether the listed addresses are ever touched. A malicious client submits a valid transferWithMemo call alongside a large number of fabricated access-list entries. The server co-signs and broadcasts the transaction. The intended transfer executes normally, but the fee-payer wallet pays a large multiple of the expected gas cost with no corresponding on-chain work. At the maintainer's default of 137 access-list entries (fitting within Bandit's 10,000-byte per-header-field limit) and 100 Gwei max_fee_per_gas, per-payment gas cost rises from ~51,287 to ~380,087 gas, a 7.4x multiplier. Sustained abuse destroys the sponsor's operating margin on low-cost payments and, over time, drains the fee-payer wallet. This issue affects mpp: from 0.2.0 before 0.6.0.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00382 32nd percentileScored 2026-11-07

Fix Fixed mpp (ZenHive): 0.6.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
ZenHive	mpp	0.2.0 to before 0.6.0	0.6.0	Patch available	CNA

mpp VendorZenHive Affected 0.2.0 to before 0.6.0 Fixed in 0.6.0 Patch available CNA

CPE names CNA · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:ZenHive:mpp::::::::	—	—	—

cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:* Versions — — ·—

Remediation

Fix · CNA mpp (ZenHive) Fixed in 0.6.0

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

Release · 2026-07-17
ZenHive mpp 0.6.0
3 records Highest priority Priority HIGH 3 HIGH
Other records, highest priority first
- TI-2026-42571 Unbounded max_fee_per_gas in mpp Tempo fee-payer enables single-request wallet drainPriority HIGH 71
- TI-2026-42392 Missing gas_limit validation in mpp Tempo fee-payer enables wallet drainPriority HIGH 69
Show all 3 records →
Release · 2026-07-17
ZenHive mpp 5d6338e2334084c5f2a78cfcca474830733ed7e8
2 records Highest priority Priority HIGH 2 HIGH
Other records, highest priority first
- TI-2026-42571 Unbounded max_fee_per_gas in mpp Tempo fee-payer enables single-request wallet drainPriority HIGH 71
Show all 2 records →

Timeline

2026-10-02 Threatist record created from CVE-2026-59694
2026-10-03 Alias added: GHSA-r4hx-mhrp-xf73

References

Patch 1

https://github.com/ZenHive/mpp/commit/5d6338e2334084c5f2a78cfcca474830733ed7e8

Advisory 1

https://github.com/ZenHive/mpp/security/advisories/GHSA-qpxh-ff8m-c62v

Other 2

TI-2026-42571 Unbounded max_fee_per_gas in mpp Tempo fee-payer enables single-request wallet drain CVSS 4.0HIGH 8.3
TI-2026-42392 Missing gas_limit validation in mpp Tempo fee-payer enables wallet drain CVSS 4.0HIGH 8.2
TI-2026-60473 Session voucher adding no new funds is accepted without a charge in mpp, serving paid resources for free CVSS 4.0HIGH 7.1
TI-2026-47746 On-chain transfer proof is not single-use in mpp EVM payment method, enabling cross-challenge replay CVSS 4.0HIGH 8.7
TI-2026-51635 Resource allocation without limits in ZenHive mpp CVSS 4.0HIGH 8.3
TI-2026-57069 Unbounded key authorization in mpp Tempo fee-payer sponsorship inflates gas cost and sponsors access-key provisioning CVSS 4.0HIGH 8.3

See all 12 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences