CVE-2026-40196 HomeBox has Unauthorized API Access via Retained defaultGroup ID After Group Access Revocation
Attackers with revoked group access can bypass API controls to read and modify group data due to retained default group IDs.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-40196?
CVE-2026-40196 is a high-severity missing authorization vulnerability in sysadminsmedia homebox, published on 17 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
HomeBox is a home inventory and organization system. Versions prior to 0.25.0 contain a vulnerability where the defaultGroup ID remained permanently assigned to a user after being invited to a group, even after their access to that group was revoked. While the web interface correctly enforced the access revocation and prevented the user from viewing or modifying the group's contents, the API did not. Because the original group ID persisted as the user's defaultGroup, and this value was not properly validated when the X-Tenant header was omitted, the user could still perform full CRUD operations on the group's collections through the API, bypassing the intended access controls. This issue has been fixed in version 0.25.0.
Weakness: CWE-708
Which versions are affected by CVE-2026-40196?
It affects 1 product.
Products include Sysadminsmedia Homebox.
How do I fix CVE-2026-40196?
No fix has been published for CVE-2026-40196 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-40196 being exploited?
There is no known exploitation of CVE-2026-40196 in the wild and no public exploit code.
Other vulnerabilities in sysadminsmedia homebox
Sources
Also known as GHSA-6pvm-v73p-p6m9.