CVE-2026-71537

MEDIUM 6.5

Paymenter: Credit-refund double-spend race condition in service downgrade (doUpgrade)

CVSS Score

6.5

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-362
Vendor	paymenter
Product	paymenter
Published	Sep 18, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Affected Versions

Paymenter / Paymenter

< 1.5.7

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/Paymenter/Paymenter/security/advisories/GHSA-5gmm-hjfj-8ff7 github.com: https://github.com/Paymenter/Paymenter/commit/a42e7f8bafce054ad70de3a2c2ac94d13579f41b github.com: https://github.com/Paymenter/Paymenter/releases/tag/v1.5.7