CVE-2026-73829

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Source
https://cve.org/CVERecord?id=CVE-2026-73829
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-73829.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-73829
Aliases
Published
2026-08-19T17:19:43.696Z
Modified
2026-08-20T03:55:12.341251497Z
Severity
  • 6.3 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N CVSS Calculator
Summary
Non-atomic hash-credential dedup in mpp Tempo allows replay of a confirmed payment under a concurrent race
Details

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: checkhashunused/2 reads the dedup store, an ethgetTransactionReceipt round trip verifies the payment on chain, and only then does markhashused/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 checkand_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.

Database specific 
{
    "unresolved_ranges": [
        {
            "extracted_events": [
                {
                    "introduced": "f8904666061fbab695874856d8fcd02c471dfe1b"
                },
                {
                    "fixed": "46c5b0e1311da7d92190dc7d9ea89027a1d365e9"
                }
            ],
            "source": "AFFECTED_FIELD"
        }
    ],
    "cna_assigner": "EEF",
    "cwe_ids": [
        "CWE-367"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73829.json"
}
References

Affected packages

Git / github.com/zenhive/mpp

Affected ranges

Type
GIT
Repo
https://github.com/zenhive/mpp
Events
Introduced
7ca7538f05959a98e0e5e63e4bd949b4f362cf8d
Fixed
542a525563c2fcedd670b593437deca81c6797a4
Database specific
Show details 
{
    "extracted_events": [
        {
            "introduced": "0.2.0"
        },
        {
            "fixed": "0.6.1"
        }
    ],
    "source": "AFFECTED_FIELD"
}

Affected versions

v0.*
v0.2.0
v0.3.0
v0.4.0
v0.5.1
v0.6.0

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-73829.json"