Paymenter has a credit-refund double-spend race condition in service downgrade (doUpgrade) — GHSA-5GMM-HJFJ-8FF7

Summary

### Summary The service downgrade implementation in `app/Livewire/Services/Upgrade.php::doUpgrade()` executes a proration calculation and a subsequent user credit refund without any transactional safety or database locks. The only concurrency check relies on an unisolated database query checking for existing pending upgrades. Because there is no active database transaction or pessimistic row-level lock spanning…

Timeline

Published by source

2026-09-18

Risk context

• Reported severity or threat level: medium.
• Reported CVSS score: 6.5 out of 10.
• Review exposure for the affected product or family: composer: paymenter/paymenter.

Product

composer: paymenter/paymenter

What to do

General, cautious steps (verify details in the official source):

• Review exposure and plan remediation based on risk and environment.
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

Evidence and provenance

Canonical advisory ID

GHSA-5GMM-HJFJ-8FF7

Source

GitHub

Vendor

GitHub

Published by source

2026-09-18

Last source activity

2026-09-18

Additional identifiers

CVE-2026-71537

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.