CVE-2026-39311
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedTrilium 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceTrilium Notes versions 0.102.1 and prior allow unauthenticated RCE through a chain involving unsanitized SVG attachments served with image/svg+xml MIME type, disabled Helmet CSP middleware, and a reachable /api/script/exec endpoint. Attackers exploit the Same-Origin Policy in malicious SVG to extract the csrfToken and execute arbitrary Node.js code by tricking authenticated users into viewing shared SVG attachments.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- High
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:C/C:L/I:L/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check installed Trilium Notes versionLocate the version number in the Trilium application (typically visible in the About section or in the package.json/server info). Compare it against the affected range: versions 0.102.1 and prior are vulnerable.Affected if Installed version is 0.102.1 or any prior version (0.102.0, 0.101.x, etc.)
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Verify Helmet CSP middleware statusInspect the Trilium configuration files or server startup settings to determine whether Content Security Policy middleware (Helmet CSP) is enabled or explicitly disabled.Affected if CSP middleware is explicitly disabled in the configuration, removing a protective layer against XSS attacks.
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Confirm script execution API accessibilityCheck whether the /api/script/exec endpoint is enabled and accessible in the Trilium instance. This may be visible in server routing configuration or API documentation.Affected if The /api/script/exec endpoint is active and available, allowing the second stage of the attack chain.
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Identify SVG attachment handlingDetermine if the system is configured to serve SVG attachments with the image/svg+xml MIME type, which enables the XSS vector.Affected if SVG attachments are served with image/svg+xml MIME type without sanitization, allowing malicious SVG execution.
A user is affected if their Trilium Notes version is 0.102.1 or earlier AND CSP is disabled AND the script execution API is accessible AND SVG attachments are served with the image/svg+xml MIME type.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade to Trilium Notes version 0.102.2 or later which includes the fix; verify CSP is enabled and consider implementing SVG sanitization as defense-in-depth.
0.102.2
- 1. Back up the Trilium Notes data directory (the directory containing your notes database) before proceeding with the upgrade.
- 2. Stop the running Trilium Notes server instance.
- 3. Download version 0.102.2 of Trilium Notes from the official GitHub releases page (github.com/zadam/trilium).
- 4. Replace the existing Trilium application files with the new version 0.102.2 files, preserving your data directory configuration.
- 5. Start the Trilium Notes server with the updated application files.
- 6. Verify that the server starts successfully and you can access your notes.
- 7. Confirm that SVG attachments are now properly sanitized and CSP headers are enabled (check browser developer tools Network tab for Content-Security-Policy header).
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-39311 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-39311 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
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- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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