CVE-2026-42451
6.3 · MEDIUMOverview
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.
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's AI-powered security agents can automatically detect CVE-2026-42451 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
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Browser-based exploitation validates findings with real proof-of-concept.
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