CVE-2026-42451
MediumCVSS 6.3Exploitation Probability (EPSS)
Low risk3th percentile - higher than 3% of all known CVEs
Summary
Grimmory, a self-hosted digital library, prior to version 2.3.1 contains a stored cross-site scripting (XSS) vulnerability in its browser-based EPUB reader. This allows an attacker to embed arbitrary JavaScript in a crafted EPUB file. When a victim opens the book, the script executes in their browser with full access to the Grimmory application's session context. This can enable session token theft and account takeover, including administrative access if an administrator opens the affected book. This issue has been patched in version 2.3.1.
Risk Assessment
The risk includes session token theft and account takeover, including administrative accounts, which can lead to full compromise of the Grimmory instance.
Recommendation
It is recommended to immediately update Grimmory to version 2.3.1 or later, which contains a fix for this vulnerability.
Other vulnerabilities in Grimmory
See all- CVE-2026-93955Medium
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.
- CVE-2026-93954Medium
A security vulnerability has been detected in grimmory-tools grimmory up to 3.3.3/3.4.1. Affected is the function AppSettingController.getAppSettings of the file backend/src/main/java/org/booklore/controller/AppSettingController.java of the component Settings API Endpoint. Such manipulation leads to incorrect authorization. The attack can be launched remotely. The exploit has been disclosed publicly and may be used. The name of the patch is 2b66ca6df8110f6b512e030b54c16b9fbe318f17. Applying a patch is advised to resolve this issue.
Original NVD description (English source)
Grimmory is a self-hosted digital library. Prior to version 2.3.1, a stored cross-site scripting (XSS) vulnerability in Grimmory's browser-based EPUB reader allows an attacker to embed arbitrary JavaScript in a crafted EPUB file. When a victim opens the book, the script executes in their browser with full access to the Grimmory application's session context. This can enable session token theft and account takeover, including administrative access if an administrator opens the affected book. This issue has been patched in version 2.3.1.