CVE-2026-43927 — FOSSBilling has race condition in cart checkout that bypasses promo code usage limits
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 app…
Published: 2026-07-06 · CVSS: 6.9 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7