---
cve: "CVE-2026-73829"
severity: "MEDIUM"
cvss: 6.3
epss: "24%"
vendor: "ZenHive"
kev: false
exploited: false
published: "2026-08-19 18:17:25"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-16T11:20:34+02:00"
---

# CVE-2026-73829

> 6.3 MEDIUM · 🧪 PoC

## Beschreibung

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.

## CVSS-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 542a525563c2fcedd670b593437deca81c6797a4 (Commit)
- 46c5b0e1311da7d92190dc7d9ea89027a1d365e9 (Commit)

## Referenzen

- <https://github.com/ZenHive/mpp/security/advisories/GHSA-w8j7-7qc3-5f24>
- <https://cna.erlef.org/cves/CVE-2026-73829.html>
- <https://osv.dev/vulnerability/EEF-CVE-2026-73829>
- <https://github.com/ZenHive/mpp/commit/46c5b0e1311da7d92190dc7d9ea89027a1d365e9>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-73829) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_