What is CVE-2026-42451?

CVE-2026-42451 is a medium-severity vulnerability in Grimmory-tools Grimmory, classified under Cross-site Scripting. CVSS score: 6.3/10. Published 2026-05-08.

How severe is CVE-2026-42451?

Medium severity. CVSS v3 base score is 6.3 out of 10.

XSS in Grimmory-tools Grimmory

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 vi…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.000 (0.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L.

Affected products

Grimmory-tools Grimmory — versions < 2.3.1

Weakness classification (CWE)

References

security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-42451?: CVE-2026-42451 is a medium-severity vulnerability in Grimmory-tools Grimmory, classified under Cross-site Scripting. CVSS score: 6.3/10. Published 2026-05-08.
How severe is CVE-2026-42451?: Medium severity. CVSS v3 base score is 6.3 out of 10.