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CVE-2026-42451

6.3 · MEDIUM

Grimmory is a self-hosted digital library.

Published May 8, 2026CWE-79EPSS 0.15%

Overview

CVE-2026-42451 is a medium-severity vulnerability. It was published on May 8, 2026 and has a CVSS 3.1 base score of 6.3 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 6.3, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/grimmory-tools/grimmory/releases/tag/v2.3.1GitHubgithub.com/grimmory-tools/grimmory/security/advisories/GHSA-frv6-5wq5-9p24

How CyberStrike helps

Frequently asked questions

What is CVE-2026-42451?

CVE-2026-42451 is a medium-severity vulnerability. It was published on May 8, 2026 and has a CVSS 3.1 base score of 6.3 (MEDIUM).

How severe is CVE-2026-42451?

This vulnerability has a CVSS 3.1 base score of 6.3, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-42451?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-42451?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-42451 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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