What is CVE-2026-91021?

CVE-2026-91021 is a medium-severity vulnerability in Trilium Trillium Notes, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-09-14.

How severe is CVE-2026-91021?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Trilium Trillium Notes

CVE-2026-91021

Trilium Notes, version v0.103.0 and earlier, contains a stored cross-site scripting (XSS) vulnerability in the share renderer for webView notes due to improper HTML escaping of user-controlled #webViewSrc values. This vulnerability allows attackers with note-authoring privileges to inject arbitrary JavaScript that executes for any user who opens the shared note, including administrators.

Vulnerability class: XSS (Cross-Site Scripting)

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

Affected products

Trilium Trillium Notes

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

cret@cert.org

Frequently asked questions

What is CVE-2026-91021?: CVE-2026-91021 is a medium-severity vulnerability in Trilium Trillium Notes, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-09-14.
How severe is CVE-2026-91021?: Medium severity. CVSS v3 base score is 5.4 out of 10.