CVE-2026-88255

mpp · Vulnerability

CVSS 4.0 6.3 MEDIUMCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-88255

Published

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.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-88255

Published

mpp

https://repo.hex.pm

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "collectionURL": "https://repo.hex.pm",
                    "cpes": [
                        "cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "'Elixir.MPP.Methods.Tempo'"
                    ],
                    "packageName": "mpp",
                    "packageURL": "pkg:hex/mpp",
                    "product": "mpp",
                    "programFiles": [
                        "lib/mpp/methods/tempo.ex"
                    ],
                    "programRoutines": [
                        {
                            "name": "'Elixir.MPP.Methods.Tempo':verify/2"
                        }
                    ],
                    "repo": "https://github.com/ZenHive/mpp",
                    "vendor": "ZenHive",
                    "versions": [
                        {
                            "lessThan": "0.16.2",
                            "status": "affected",
                            "version": "0.2.0",
                            "versionType": "semver"
                        }
                    ]
                }

zenhive/mpp

https://github.com

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "collectionURL": "https://github.com",
                    "cpes": [
                        "cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "'Elixir.MPP.Methods.Tempo'"
                    ],
                    "packageName": "zenhive/mpp",
                    "packageURL": "pkg:github/zenhive/mpp",
                    "product": "mpp",
                    "programFiles": [
                        "lib/mpp/methods/tempo.ex"
                    ],
                    "programRoutines": [
                        {
                            "name": "'Elixir.MPP.Methods.Tempo':verify/2"
                        }
                    ],
                    "repo": "https://github.com/ZenHive/mpp",
                    "vendor": "ZenHive",
                    "versions": [
                        {
                            "lessThan": "e12bd4a1cea2e97c2a01fc059c48e5594a7b4a43",
                            "status": "affected",
                            "version": "f8904666061fbab695874856d8fcd02c471dfe1b",
                            "versionType": "git"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON