CVE-2026-93955 grimmory-tools grimmory Download Endpoint KoboController.java streamFileToResponse authorization
Remote attackers can bypass authorization checks in the download endpoint to access unauthorized book files via manipulated bookId parameters.
- 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-2026-93955?
CVE-2026-93955 is a medium-severity missing authorization vulnerability in grimmory-tools grimmory, published on 19 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
A vulnerability was detected in grimmory-tools grimmory up to 3.3.3/3.4.1. Affected by this vulnerability is the function streamFileToResponse of the file backend/src/main/java/org/booklore/controller/KoboController.java of the component Download Endpoint. Performing a manipulation of the argument bookId results in authorization bypass. The attack may be initiated remotely. The exploit is now public and may be used. Issue #2431 is closed as completed, but its only comment states that the issue “has already been reported elsewhere.” No fixing commit or pull request is identified there.
Which versions are affected by CVE-2026-93955?
How do I fix CVE-2026-93955?
No fix has been published for CVE-2026-93955 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-2026-93955 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-93955 exists.
Sources
Also known as GHSA-frhf-rqp4-m3jc.