The type="hash" credential path in MPP.Methods.Tempo.verify/2 guards against replay with a non-atomic check-then-mark sequence: check_hash_unused/2 reads the dedup store, an eth_getTransactionReceipt round trip verifies the payment on chain, and only then does mark_hash_used/2 write the mark. Concurrent requests carrying the same settled payment hash all pass the read before any of them writes, so each is issued a receipt. The store's atomic check_and_mark/2 primitive is available and used by the type="transaction" path, but the hash path calls plain get and put even when the configured store implements it. Exploitation requires a dedup store to be configured; the default nil store is stateless and documented as offering no replay protection at all.
This issue affects mpp: from 0.2.0 before 0.6.1.
No advisories yet.
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
Wed, 19 Aug 2026 20:30:00 +0000
| Type | Values Removed | Values Added |
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| Metrics |
ssvc
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Wed, 19 Aug 2026 17:30:00 +0000
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| Description | Time-of-check Time-of-use (TOCTOU) Race Condition in ZenHive mpp allows an unauthenticated remote client to redeem one confirmed on-chain payment for multiple paid-resource accesses. The type="hash" credential path in MPP.Methods.Tempo.verify/2 guards against replay with a non-atomic check-then-mark sequence: check_hash_unused/2 reads the dedup store, an eth_getTransactionReceipt round trip verifies the payment on chain, and only then does mark_hash_used/2 write the mark. Concurrent requests carrying the same settled payment hash all pass the read before any of them writes, so each is issued a receipt. The store's atomic check_and_mark/2 primitive is available and used by the type="transaction" path, but the hash path calls plain get and put even when the configured store implements it. Exploitation requires a dedup store to be configured; the default nil store is stateless and documented as offering no replay protection at all. This issue affects mpp: from 0.2.0 before 0.6.1. | |
| Title | Non-atomic hash-credential dedup in mpp Tempo allows replay of a confirmed payment under a concurrent race | |
| First Time appeared |
Zenhive
Zenhive mpp |
|
| Weaknesses | CWE-367 | |
| CPEs | cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Zenhive
Zenhive mpp |
|
| References |
| |
| Metrics |
cvssV4_0
|
Projects
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Status: PUBLISHED
Assigner: EEF
Published:
Updated: 2026-08-19T18:58:33.322Z
Reserved: 2026-08-17T11:15:02.320Z
Link: CVE-2026-73829
Updated: 2026-08-19T18:57:34.178Z
Status : Received
Published: 2026-08-19T18:17:25.800
Modified: 2026-08-19T19:17:24.470
Link: CVE-2026-73829
No data.
OpenCVE Enrichment
No data.