CVE-2026-43927
FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, a race condition in the cart checkout flow allows an authenticated client to apply a promo code beyond its configured maximum uses. By sending concurrent checkout requests before any single request completes the usage increment, a client can obtain unlimited discounted or free orders from a single-use or limited-use promo code. Version 0.8.0 patches the issue. Some workarounds are available. Disable promo codes entirely until a patch is available or monitor the promo table for used values exceeding maxuses and manually review affected orders.
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Exploitation outlook
- Low exploitation risk0.22% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 12% of all EPSS-scored CVEs.
Advisory coverage (1)
External references
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[](https://www.csirts.com/cve/CVE-2026-43927)