# CVE-2026-73541: Denial of service in mpp

> An unauthenticated attacker can drain a sponsor wallet via concurrent transactions, causing denial of service for legitimate users.

- **Severity:** High 8.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Aug 2026
- **Updated:** 19 Aug 2026
- **Also known as:** EEF-CVE-2026-73541, GHSA-j4j7-7xpr-c7cr, GHSA-j5gr-9qmc-3234

## What is CVE-2026-73541?

CVE-2026-73541 is a high-severity denial of service vulnerability in ZenHive mpp, published on 19 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Allocation of Resources Without Limits or Throttling in ZenHive mpp allows an unauthenticated remote client to drain the fee-payer wallet through concurrent sponsored payments, denying service to legitimate payers once it is empty.

MPP.Methods.Tempo.FeePayerPolicy enforces its ceilings (max_gas, max_fee_per_gas, max_priority_fee_per_gas, the worst-case gas_limit * max_fee_per_gas <= max_total_fee budget cap, and a validity window) against one transaction at a time, and nothing accounts for exposure across concurrent requests. reserve_hash_atomic/2 is keyed on the transaction hash, so it prevents duplicate broadcast of the same signed transaction but not N distinct sponsored transactions carrying distinct expiring nonces. Committed sponsor exposure is therefore N times max_total_fee, bounded by nothing in the library, and the default 900 second validity window lets co-signed transactions stay broadcastable and uncounted for that entire period.

This issue affects mpp: from 0.2.0 before 0.12.0.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-73541?

1 open source package ship an affected version, including mpp. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mpp` | Hex | From 0.2.0 | 0.12.0 |

Products: Zenhive Machine Payments Protocol.

## How do I fix CVE-2026-73541?

Upgrade mpp to 0.12.0 or later.

## Is CVE-2026-73541 being exploited?

There is no known exploitation of CVE-2026-73541 in the wild and no public exploit code.

## Other vulnerabilities in ZenHive mpp

- [CVE-2026-67581](https://insights.sbomify.com/CVE-2026-67581/): On-chain transfer proof is not single-use in mpp EVM payment method, enabling cross-challenge replay (high 8.7)
- [CVE-2026-73136](https://insights.sbomify.com/CVE-2026-73136/): Static memo configuration in mpp Tempo disables per-challenge attribution binding, enabling third-party replay (high 8.2)
- [CVE-2026-73829](https://insights.sbomify.com/CVE-2026-73829/): Non-atomic hash-credential dedup in mpp Tempo allows replay of a confirmed payment under a concurrent race (medium 6.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-73541 and fix it if it is affected.

What it is: CVE-2026-73541 is a high-severity denial of service vulnerability in ZenHive mpp, published on 19 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-73541 in the wild and no public exploit code.

Affected packages and fixed versions:
- mpp (Hex): affected from 0.2.0; fixed in 0.12.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-73541/ (Markdown: https://insights.sbomify.com/CVE-2026-73541/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73541
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73541
- OSV: https://osv.dev/vulnerability/CVE-2026-73541

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-73541/
Summaries are generated and may contain mistakes; the official description above is the record.