Unbounded max_fee_per_gas in mpp Tempo fee-payer enables single-request wallet drain
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · High
- 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 drain the fee-payer wallet in a single request by naming an arbitrarily high gas price. 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 max_fee_per_gas and max_priority_fee_per_gas, without validating that they are within reasonable bounds. A malicious client embeds arbitrarily large values for these fields in the signed envelope. The server co-signs and broadcasts the transaction. The effective_gas_price billed against the fee-payer wallet is derived from the attacker-supplied ceilings, so the server pays those inflated per-gas rates out of its own wallet. A single crafted request can drain the wallet entirely, after which the server can no longer sponsor gas for legitimate payment requests. This issue affects mpp: from 0.2.0 before 0.6.0.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Total
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 ·
ZenHive mpp 0.6.0
3 records Highest priority Priority HIGH 3 HIGH
Other records, highest priority first
- TI-2026-42570 Unbounded access list in mpp Tempo fee-payer inflates gas cost per paymentPriority HIGH 69
- TI-2026-42392 Missing gas_limit validation in mpp Tempo fee-payer enables wallet drainPriority HIGH 69
- Release ·
ZenHive mpp 5d6338e2334084c5f2a78cfcca474830733ed7e8
2 records Highest priority Priority HIGH 2 HIGH
Other records, highest priority first
- TI-2026-42570 Unbounded access list in mpp Tempo fee-payer inflates gas cost per paymentPriority HIGH 69
Timeline
- 2026-10-02 Threatist record created from CVE-2026-59695
- 2026-10-03 Alias added: GHSA-6v7f-h3qg-wwpp
References
More ZenHive vulnerabilities
- TI-2026-42570 Unbounded access list in mpp Tempo fee-payer inflates gas cost per payment 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
Sources
- CVE-2026-59695 · CVE Program
- CVE-2026-59695 · NVD
- FIRST EPSS
- GHSA-6v7f-h3qg-wwpp · GitHub Advisory Database · CC BY 4.0
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