CVE-2026-43927

Summary

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.

Affected Software

VendorProductVersion RangeStatus
FOSSBillingFOSSBilling< 0.8.0affected

Weaknesses

  • CWE-367: CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References