Authentication Bypass by Capture-replay in ZenHive mpp allows an attacker holding a captured subscription activation credential to charge the payer repeatedly.
The payer signs a Tempo KeyAuthorization over the chain id, key type, key id, expiry, limits and scopes only, with nothing tying it to the challenge that prompted it. MPP.Methods.Tempo.KeyAuthorization.verify/3 in lib/mpp/methods/tempo/key_authorization.ex pins each of those signed fields against the subscription request, and the access key it pins is a static per-endpoint server key, so one signed authorization verifies against every challenge the server issues for the same subscription terms. MPP.Methods.Tempo.Subscription.activate/4 deduplicates activations by challenge id, so presenting the captured credential under a fresh challenge produces a different dedup key, claim_activation succeeds, and the subscription transaction is built and broadcast again. Each replay charges the payer's wallet a new first-period settlement and re-authorizes the server key, bounded only by the subscription expiry and the chain's own semantics for re-installing an existing key.
This issue affects mpp: from 0.14.0 before 0.16.2.
{
"cna_assigner": "EEF",
"cwe_ids": [
"CWE-294"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/87xxx/CVE-2026-87119.json",
"unresolved_ranges": [
{
"extracted_events": [
{
"introduced": "db464dfa9a86ccda58f0827101f6da6bd8aafa78"
},
{
"fixed": "4b6eaec02af0e8485cfb4ff68f467d075ed5dd6f"
}
],
"source": "AFFECTED_FIELD"
}
]
}