# CVE-2026-39311: Trilium Notes: Stored XSS Leads to Unauthorized Remote Code Execution (RCE) via Unsanitized SVG Attachments

> Attackers can achieve remote code execution by tricking users into viewing unsanitized SVG attachments, exploiting disabled CSP and exposed APIs.

- **Severity:** Medium 6.8 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:C/C:L/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 20 May 2026
- **Updated:** 20 May 2026
- **Also known as:** GHSA-p837-cxw3-m964

## What is CVE-2026-39311?

CVE-2026-39311 is a medium-severity cross-site scripting vulnerability in TriliumNext Trilium, published on 20 May 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-94 (Improper Control of Generation of Code), CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-39311?


## How do I fix CVE-2026-39311?

No fix has been published for CVE-2026-39311 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-39311 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39311 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39311 and fix it if it is affected.

What it is: CVE-2026-39311 is a medium-severity cross-site scripting vulnerability in TriliumNext Trilium, published on 20 May 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39311 exists.

Affected product: TriliumNext Trilium. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-39311/ (Markdown: https://insights.sbomify.com/CVE-2026-39311/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39311
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39311
- OSV: https://osv.dev/vulnerability/CVE-2026-39311

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-39311/
Summaries are generated and may contain mistakes; the official description above is the record.