VulnerabilityDeferred

CVE-2026-43927

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.

MEDIUM 6.9EPSS 0.33%

Does this matter?

Lower severity and a low EPSS score (0.33%). Track it; it rarely justifies an emergency change on its own.

Description

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.

CVSS 4.0: 6.9 MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.33% probability · 26th percentile
CISA KEV: Not listed
Weakness: CWE-367
Source: security-advisories@github.com

References

https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-w898-cx35-25gh

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.