# CVE-2026-43925: FOSSBilling: Mass assignment of group_id in guest client registration allows unauthorized promo code use

> Unauthenticated attackers can assign themselves to privileged client groups during registration to bypass restrictions and use unauthorized promo codes.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Jul 2026
- **Updated:** 7 Jul 2026
- **Also known as:** GHSA-q4rq-9844-r9w2

## What is CVE-2026-43925?

CVE-2026-43925 is a medium-severity missing authorization vulnerability in FOSSBilling, published on 6 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, an unauthenticated mass assignment vulnerability in the client self-registration endpoint allows any visitor to assign themselves to an arbitrary client group during sign-up. Because client groups can gate promo code eligibility, an attacker may apply group-restricted discount codes and receive unauthorized discounts. Version 0.8.0 contains a patch. As a workaround, administrators can either remove group restrictions from promo codes or disable client self-registration (Settings → Clients → Disable signup).

Weakness: CWE-915 (Improperly Controlled Modification of Dynamically-Determined Object Attributes)

## Which versions are affected by CVE-2026-43925?


## How do I fix CVE-2026-43925?

No fix has been published for CVE-2026-43925 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-43925 being exploited?

There is no known exploitation of CVE-2026-43925 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43925 and fix it if it is affected.

What it is: CVE-2026-43925 is a medium-severity missing authorization vulnerability in FOSSBilling, published on 6 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-43925 in the wild and no public exploit code.

Affected product: FOSSBilling. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-43925/ (Markdown: https://insights.sbomify.com/CVE-2026-43925/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43925
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43925
- OSV: https://osv.dev/vulnerability/CVE-2026-43925

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43925/
Summaries are generated and may contain mistakes; the official description above is the record.