# CVE-2026-43918: Auth bypass in FOSSBilling

> Suspended or inactive users retain access via existing sessions and tokens because status checks are missing, allowing unauthorized access to billing data.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Jul 2026
- **Updated:** 8 Jul 2026
- **Also known as:** CVE-2026-43919, GHSA-qv6c-v49w-8g2j

## What is CVE-2026-43918?

CVE-2026-43918 is a high-severity authentication bypass vulnerability in FOSSBilling, published on 6 Jul 2026. Any signed-in user can exploit it over the network, 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, when a client or staff/admin account is suspended or marked inactive, existing authenticated sessions are not invalidated. The session identity loaders in src/di.php (loggedin_client and loggedin_admin) only reject sessions if the backing account record no longer exists in the database. They do not verify that the account's status is still active. This allows a suspended or deactivated user to retain full access until their session naturally expires. This issue has been fixed in version 0.8.0.

Weakness: CWE-613 (DEPRECATED: Insufficient Session Expiration)

## Which versions are affected by CVE-2026-43918?


## How do I fix CVE-2026-43918?

No fix has been published for CVE-2026-43918 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-43918 being exploited?

There is no known exploitation of CVE-2026-43918 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43918 and fix it if it is affected.

What it is: CVE-2026-43918 is a high-severity authentication bypass vulnerability in FOSSBilling, published on 6 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-43918 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-2026-43918/ (Markdown: https://insights.sbomify.com/CVE-2026-43918/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43918
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43918
- OSV: https://osv.dev/vulnerability/CVE-2026-43918

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43918/
Summaries are generated and may contain mistakes; the official description above is the record.