---
id: "CVE-2026-128042"
page: "https://infrastack.ai/live/CVE-2026-128042"
kind: "vulnerability"
aliases: ["CVE-2026-128042"]
title: "OpenMage magento-lts: race condition lets coupons be redeemed past their cap"
severity: "medium"
cvss: 6.3
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["ecommerce", "magento-lts", "openmage", "runtime", "self-hosted"]
not_affected_if: ["fixed-version", "no-usage-limited-coupons"]
published_at: "2026-11-13T10:18:09+00:00"
first_seen_at: "2026-11-13T10:47:32+00:00"
updated_at: "2026-11-13T10:55:11+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-128042", "first_seen_at": "2026-11-13T10:47:32+00:00"}]
exploit_sources: []
---

# OpenMage magento-lts: race condition lets coupons be redeemed past their cap

Link for people: https://infrastack.ai/live/CVE-2026-128042 (this .md is for agents)

OpenMage magento-lts checks shopping cart coupon usage limits without a lock, and the usage counters are incremented non-atomically. Concurrent checkouts can redeem a limited coupon more times than its cap allows.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed magento-lts version in composer.json or the OpenMage admin; affected versions are before `20.19.0` and `21.0.0-beta1` through `21.0.0-beta2`.
- Review whether limited-use cart price rules are in use in the sales rules configuration.

## Fix

- magento-lts: upgrade to `20.19.0` or later
- magento-lts 21.0.0 beta line: upgrade to `21.0.0-beta3` or later

## Timeline

- 2026-11-13T10:47:32+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-128042

## Documents

- [advisory] Vendor advisory: github.com https://github.com/OpenMage/magento-lts/security/advisories/GHSA-5rg7-22cv-c9q6
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/openmage-magento-lts-before-20.19.0-race-condition-in-coupon-usage-limits
- [fix] Patch: github.com https://github.com/OpenMage/magento-lts/commit/2626f027a752cda004c5cf7f8f9bd3cf52f525f2

## From the sources

OpenMage magento-lts before 20.19.0 and 21.0.0-beta1 before 21.0.0-beta3 contains a race condition in shopping cart price rule usage limits, because Mage_SalesRule_Model_Validator checks coupon limits without locking and the usage counters are later incremented non-atomically. Unauthenticated attackers, including guest shoppers, can submit concurrent checkouts to redeem a limited coupon more times than its cap allows.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_