CVE-2026-43927
FOSSBilling has race condition in cart checkout that bypasses promo code usage limits
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.
INFO
Published Date :
July 6, 2026, 10:16 p.m.
Last Modified :
July 6, 2026, 10:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-43927
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update FOSSBilling to version 0.8.0.
- Alternatively, disable promo codes.
- Monitor promo table for usage anomalies.
- Manually review affected orders.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-43927.
| URL | Resource |
|---|---|
| https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-w898-cx35-25gh |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-43927 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-43927
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-43927 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-43927 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Jul. 06, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'FOSSBilling', 'product': 'FOSSBilling', 'versions': [{'status': 'affected', 'version': '< 0.8.0'}]}] Added 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. Added CVSS V4.0 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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-367 Added Reference https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-w898-cx35-25gh