ZenHive mpp up to 0.2.0/0.6.0 Hash Path MPP.Methods.Tempo.verify toctou

Summaryinfo

A vulnerability classified as problematic was found in ZenHive mpp up to 0.2.0/0.6.0. The impacted element is the function MPP.Methods.Tempo.verify of the component Hash Path. The manipulation results in toctou. This vulnerability is identified as CVE-2026-73829. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as problematic has been found in ZenHive mpp up to 0.2.0/0.6.0. Affected is the function MPP.Methods.Tempo.verify of the component Hash Path. The manipulation with an unknown input leads to a toctou vulnerability. CWE is classifying the issue as CWE-367. The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state. This is going to have an impact on integrity. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-73829 since 08/17/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details are known, but there is no available exploit.

Upgrading to version 0.6.1 eliminates this vulnerability.

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Productinfo

Vendor

• ZenHive

Name

• mpp

Version

• 0.1
• 0.2
• 0.2.0
• 0.3
• 0.4
• 0.5
• 0.6.0

Website

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

CPE 2.3info

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CPE 2.2info

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