CVE-2026-39311: Trilium Notes is a cross-platform, hierarchical note taking application focused on building large personal knowledge bases. Versions 0.102.1 and prior...

Description

Trilium Notes is a cross-platform, hierarchical note taking application focused on building large personal knowledge bases. Versions 0.102.1 and prior contain a critical security flaw where lack of SVG sanitization combined with a disabled Content Security Policy (CSP) and a publicly reachable backend execution API results in an unauthenticated Remote Code Execution (RCE). The vulnerability arises from an insecure-by-design architecture: Trilium serves SVG attachments with the image/svg+xml MIME type without any sanitization, and it explicitly disables Helmet's Content Security Policy middleware, removing the primary defense against script execution in served assets. Because the malicious SVG runs under the Same-Origin Policy, it can issue a fetch('/') to extract the csrfToken from the document body. With that token, it can send a signed request to /api/script/exec to execute arbitrary Node.js code on the server. An attacker can compromise the entire server instance simply by tricking an authenticated user into viewing a shared SVG attachment. The issue has been fixed in version 0.102.2.

Metrics

CVSS 3.1

6.8/10

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

EPSS Probability

0.29%

20.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

References

Timeline

Published: May 20, 2026
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-39311?

Trilium Notes is a cross-platform, hierarchical note taking application focused on building large personal knowledge bases. Versions 0.102.1 and prior contain a critical security flaw where lack of SVG sanitization combined with a disabled Content Security Policy (CSP) and a publicly reachable backend execution API results in an unauthenticated Remote Code Execution (RCE). The vulnerability arises from an insecure-by-design architecture: Trilium serves SVG attachments with the image/svg+xml MIME type without any sanitization, and it explicitly disables Helmet's Content Security Policy middleware, removing the primary defense against script execution in served assets. Because the malicious SVG runs under the Same-Origin Policy, it can issue a fetch('/') to extract the csrfToken from the document body. With that token, it can send a signed request to /api/script/exec to execute arbitrary Node.js code on the server. An attacker can compromise the entire server instance simply by tricking an authenticated user into viewing a shared SVG attachment. The issue has been fixed in version 0.102.2.

How severe is CVE-2026-39311?

CVE-2026-39311 has a CVSS score of 6.8/10 (MEDIUM severity). The EPSS model estimates a 0.29% probability of exploitation in the next 30 days.

How do I fix CVE-2026-39311?

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.