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CVE-2026-42451

MEDIUMCVSS 6.3/10EPSS 0.14%

Last modified

CVE-2026-42451 is a medium-severity vulnerability rated 6.3/10 on the CVSS scale. 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. EPSS estimates a 0.14% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
6.3/10

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

EPSS Probability
0.14%

3.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-42451?
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.
How severe is CVE-2026-42451?
CVE-2026-42451 has a CVSS score of 6.3/10 (MEDIUM severity). The EPSS model estimates a 0.14% probability of exploitation in the next 30 days.
How do I fix CVE-2026-42451?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-42451?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST