CVE-2026-42451

MEDIUM

Grimmory: Stored XSS via Malicious EPUB Enables Session Token Theft

Title source: cna

Description

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.

References (2)

Core 2

Core References

X_Refsource_Confirm x_refsource_confirm

https://github.com/grimmory-tools/grimmory/security/advisories/GHSA-frv6-5wq5-9p24

X_Refsource_Misc x_refsource_misc

http://github.com/grimmory-tools/grimmory/releases/tag/v2.3.1

Scores

CVSS v3 6.3

EPSS 0.0001

EPSS Percentile 0.7%

Attack Vector LOCAL

CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact total

Details

CWE

CWE-79 CWE-80

Status published

Products (1)

grimmory-tools/grimmory < 2.3.1

Published May 08, 2026

Tracked Since May 09, 2026