CVE-2026-93955 Details
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.
An authorization bypass vulnerability has been identified in the Grimmory Tools application, specifically in versions through 3.3.3 and 3.4.1. The issue arises in the Kobo download endpoint, where the function responsible for streaming files to the response fails to enforce proper library access controls. This vulnerability allows users with the syncKobo permission to download EPUB or CBX files from libraries to which they are not assigned, by manipulating the book ID in the download request.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 19, 2026CISA-ADP
Assessed Sep 21, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/grimmory-tools/grimmory/issues/2431#issuecomment-5384402858 | CISA-ADP | ExploitIssue TrackingTechnical DescriptionVendor |
| https://github.com/grimmory-tools/grimmory/ | [email protected] | ProductVendor |
| https://github.com/grimmory-tools/grimmory/issues/2431 | [email protected] | ExploitIssue TrackingTechnical DescriptionVendor |
| https://github.com/grimmory-tools/grimmory/issues/2431#issuecomment-5384402858 | [email protected] | ExploitIssue TrackingTechnical DescriptionVendor |
| https://vuldb.com/cve/CVE-2026-93955 | [email protected] | AdvisoryPermission Required |
| https://vuldb.com/submit/943921 | [email protected] | Permission Required |
| https://vuldb.com/vuln/407914 | [email protected] | Permission Required |
| https://vuldb.com/vuln/407914/cti | [email protected] | Content Wall |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-285 | Improper Authorization | [email protected] |
| CWE-639 | Authorization Bypass Through User-Controlled Key | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| grimmory-tools Grimmory | <= 3.3.3 (semver) <= 3.4.1 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 21, 2026 | CVE Modified | CISA-ADP |
| Sep 19, 2026 | New CVE Received | [email protected] |