Grimmory: Stored XSS via Malicious EPUB Enables Session Token Theft
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- Required
- Attack complexity
- High
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- High · High · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-79.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| grimmory-tools | grimmory | before 2.3.1 | 2.3.1 | Patch available | CNA |
- grimmory Vendorgrimmory-tools Affected before 2.3.1 Fixed in 2.3.1 Patch available CNA
Remediation
- Fix · CNA grimmory (grimmory-tools) Fixed in 2.3.1
Timeline
- 2026-10-02 Threatist record created from CVE-2026-42451
References
More grimmory-tools vulnerabilities
- TI-2026-63214 grimmory-tools grimmory Download Endpoint KoboController.java streamFileToResponse authorization CVSS 4.0MEDIUM 5.3
- TI-2026-63213 Improper authorization in grimmory-tools grimmory CVSS 4.0MEDIUM 5.3
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences