CVE-2026-33734 FOSSBilling has improper SQL neutralization in `Massmailer` recipient filters
An authenticated administrator can exploit SQL injection in FOSSBilling's Massmailer module to manipulate recipient selection queries, potentially exposing or altering data.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-33734?
CVE-2026-33734 is a medium-severity SQL injection vulnerability in FOSSBilling, published on 6 Jul 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
FOSSBilling is a free, open-source billing and client management system. Versions 0.6.0 through 0.7.2 have a SQL injection vulnerability in the `Massmailer` module filter functionality. An authenticated administrator can supply crafted filter values when updating a mass email message, causing untrusted input to be interpolated directly into SQL in the recipient selection query. Version 0.8.0 patches the issue. Some workarounds are available. Restrict administrator access to trusted users only, disable the `Massmailer` module if it is not required, audit existing records in the `mod_massmailer` table for suspicious filter values, and/or review administrator activity related to `Massmailer` message updates.
Weakness: CWE-89
Which versions are affected by CVE-2026-33734?
How do I fix CVE-2026-33734?
No fix has been published for CVE-2026-33734 yet. Limit exposure of the affected software until one is available.
Use parameterised queries everywhere and never build SQL by joining strings. Upgrade affected software first; a web application firewall only buys time. More about SQL injection.
Is CVE-2026-33734 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33734 exists.
Sources
Also known as GHSA-jf7m-j359-2899.