CVE-2026-73829: Time-of-check Time-of-use (TOCTOU) Race Condition in ZenHive mpp allows an unauthenticated remote client to re

Routine

LOW 3.7REMOTEUPGRADE

CVE-2026-73829 is a low-severity flaw (CVSS 3.7) affecting machine payments protocol. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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_

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	3.7 (Low)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 75%)
CISA exploited list	No
Weakness	CWE-367
Published	2026-08-19
Last modified	2026-09-10

Publisher (CNA): EEF · Vendor: zenhive

Last updated 2026-09-10 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-19 18:17 UTCPublished CVE record published
2026-09-10 18:30 UTCUpdated Record last modified

zenhive machine payments protocol UPGRADE

Affected: >= 0.2.0 and < 0.6.1

Fixed in: 0.6.1

Safe to downgrade to: a release before 0.2.0

1. Check installed version

apt-cache policy machine-payments-protocol || rpm -q machine-payments-protocol || machine-payments-protocol --version

2. UPGRADE to 0.6.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade machine-payments-protocol

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade machine-payments-protocol

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 0.2.0 (Debian / Ubuntu)

apt-cache madison machine-payments-protocol sudo apt install machine-payments-protocol=<VERSION_BEFORE_0.2.0> sudo apt-mark hold machine-payments-protocol

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list machine-payments-protocol sudo dnf downgrade machine-payments-protocol-<VERSION_BEFORE_0.2.0> sudo dnf versionlock add machine-payments-protocol

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-73829?

machine payments protocol: upgrade to 0.6.1. Exact commands for each OS are on this page.

Is CVE-2026-73829 being exploited?

CVE-2026-73829 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-73829 affect?

CVE-2026-73829 affects machine payments protocol. Severity is low (CVSS 3.7). 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.ver

How urgent is CVE-2026-73829?

Priority 24/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-73541 HIGH 8.2 UPGRADE Allocation of Resources Without Limits or Throttling in ZenHive mpp allows an unauthenticated remote client to
CVE-2026-73136 HIGH 7.5 UPGRADE Authentication Bypass by Capture-replay in ZenHive mpp allows an unauthenticated third party to obtain paid re
CVE-2026-67581 HIGH 7.5 UPGRADE Authentication Bypass by Capture-replay in ZenHive mpp allows an unauthenticated remote client to obtain paid

References

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