mpp: Improper Validation of Specified Quantity in Input
CVE-2026-59695 is a high-severity improper validation of specified quantity in input vulnerability in mpp from ZenHive, with a CVSS 4.0 base score of 8.3 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 0.6.0, 5d6338e2334084c5f2a78cfcca474830733ed7e8 as the first without the flaw, so updating mpp to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.38% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update mpp to 0.6.0 or 5d6338e2334084c5f2a78cfcca474830733ed7e8, whichever matches your release line, or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| ZenHive | mpp | 0.2.0 up to, but not including, 0.6.0; d29d54e507918db00a5b65d90136b73166c017d7 up to, but not including, 5d6338e2334084c5f2a78cfcca474830733ed7e8 | 0.6.0, 5d6338e2334084c5f2a78cfcca474830733ed7e8 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Attack requirements
- PresentThe target must be in a specific state or configuration for the attack to work.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- NoneNo loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- HighSerious loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- HighSerious loss of availability on the vulnerable system.
- Confidentiality (other systems)
- NoneNo loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- NoneNo loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- NoneNo loss of availability on systems beyond the vulnerable one.
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA.
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Validation of Specified Quantity in Input
The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.
More Improper Validation of Specified Quantity in Input vulnerabilities (CWE-1284)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other vulnerabilities in mpp
- 7.1 High severity
- 8.2 High severity
- 8.3 High severity
- 8.3 High severity
- 8.2 High severity
- 7.5 High severity
Recent Improper Validation of Specified Quantity in Input vulnerabilities
- 8.3 High severity
- 8.2 High severity
- 7.5 High severity
- 7.3 High severity
- 8.5 High severity
- 7.5 High severity
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