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Grimmory CVE-2026-42451

MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-05-08 GitHub_M
6.3
CVSS 3.1 · GitHub Advisory
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Severity by source

GitHub Advisory PRIMARY
6.3 MEDIUM
AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L
Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
Low

Lifecycle Timeline

1
CVE Published
May 08, 2026 - 22:51 nvd
MEDIUM 6.3

DescriptionGitHub Advisory

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.

Analysis

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.

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CVE-2026-42451 vulnerability details – vuln.today

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