CVE-2026-73136

Summary

Authentication Bypass by Capture-replay in ZenHive mpp allows an unauthenticated third party to obtain paid resources by replaying a transfer settled by an unrelated payer.

MPP.Methods.Tempo normally binds a settled TIP-20 TransferWithMemo to the specific challenge under verification through an attribution nonce carried in the memo. When a static "memo" is configured in method_config, check_matched_memo_binding/3 returns the match unconditionally and that binding is skipped, leaving only token, recipient, amount and the static memo value to match on. The static memo is echoed in every unauthenticated 402 response and Tempo transfers are public, so an attacker can take any matching transfer paid by a legitimate customer, request a fresh challenge for the same route, and present that transaction hash as a type="hash" credential. The hash path performs no sender or signature check tying the presenter to the wallet that broadcast the transfer.

This issue affects mpp: from 0.6.1 before 0.6.4.

Affected Software

VendorProductVersion RangeStatus
ZenHivempp0.6.1 < 0.6.4affected
ZenHivempp542a525563c2fcedd670b593437deca81c6797a4 < 2207d7f456ae14c1d3fcacc6f635bf4f8cee1a34affected

Weaknesses

  • CWE-294: CWE-294 Authentication Bypass by Capture-replay

Workarounds

Remove the static "memo" from the Tempo method_config so verification falls back to the default per-challenge attribution binding, which ties each settled transfer to the challenge being verified. Where a static memo must be kept, configure a dedup store (for example MPP.Tempo.ConCacheStore) with a TTL at least as long as the challenge expiry, which reduces unlimited replay to a race on the transaction hash rather than closing it.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References