ZenHive mpp up to 0.16.1 Duplicate Submission Gate lib/mpp/replay.ex reserve_hash_atomic input validation

Summaryinfo

A vulnerability was found in ZenHive mpp up to 0.16.1. It has been declared as problematic. The impacted element is the function reserve_hash_atomic of the file lib/mpp/replay.ex of the component Duplicate Submission Gate. Executing a manipulation can lead to input validation. The identification of this vulnerability is CVE-2026-88255. The attack may be launched remotely. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability has been found in ZenHive mpp up to 0.16.1 and classified as problematic. This vulnerability affects the function reserve_hash_atomic of the file lib/mpp/replay.ex of the component Duplicate Submission Gate. The manipulation with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect integrity. CVE summarizes:

Improper Validation of Unsafe Equivalence in Input in ZenHive mpp allows an unauthenticated remote client to pass the Tempo duplicate-submission gate twice with one signed transaction. MPP.Methods.Tempo reserves the pre-broadcast dedup slot on the caller-supplied hex in reserve_hash_atomic/2, keyed through store_key/1 on tx.raw rather than on a canonical form of the transaction. The deserializer stores the caller's hex verbatim and accepts both recovery-id encodings, so one signed transaction submitted once with v=27 and once with v=0 yields two distinct reserve keys, and both pass the reserve and reach the broadcast path. The plug-level credential replay store is deliberately carved out for tempo in lib/mpp/replay.ex, leaving this reserve as the only gate, and the post-broadcast mark writes the canonical hash key that the raw-keyed reserve never reads. What the duplicate submission yields depends on the node: a nonce-reuse rejection fails closed, while a node that answers with the canonical hash for an already-known transaction returns a second valid Payment-Receipt for a single on-chain payment. This issue affects mpp: from 0.2.0 before 0.16.2.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-88255 since 09/11/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available.

Upgrading to version 0.16.2 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-80256). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

• ZenHive

Name

• mpp

Version

• 0.16.0
• 0.16.1

Website

• Product: https://github.com/ZenHive/mpp/

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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