CVE-2026-71537 Paymenter: Credit-refund double-spend race condition in service downgrade (doUpgrade)
An authenticated user can exploit a race condition in service downgrades to double-spend credits, resulting in unauthorized financial gains.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-71537?
CVE-2026-71537 is a medium-severity vulnerability in Paymenter, published on 18 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Paymenter is a free and open-source webshop solution for management of hosting services. Prior to 1.5.7, app/Livewire/Services/Upgrade.php::doUpgrade() relies on Service::upgradable to check for a pending service upgrade and later executes $credit->increment('amount', abs($price)) without DB::transaction or lockForUpdate() spanning those operations. An authenticated customer with an active downgradable service can submit concurrent downgrade requests that each observe no pending upgrade, create separate upgrade records, and increment the same account credit balance, producing multiple spendable refunds for one downgrade. This issue is fixed in version 1.5.7.
Weakness: CWE-362
Which versions are affected by CVE-2026-71537?
2 open source packages ship an affected version, including paymenter/paymenter.
| Package | Affected | Fixed in |
|---|---|---|
paymenter/paymenter Packagist | All versions | 1.5.7 |
paymenter/paymenter Packagist | All versions | 1.5.7 |
How do I fix CVE-2026-71537?
Upgrade paymenter/paymenter to 1.5.7 or later.
Is CVE-2026-71537 being exploited?
There is no known exploitation of CVE-2026-71537 in the wild and no public exploit code.
Sources
Also known as GHSA-5gmm-hjfj-8ff7.