# CVE-2026-91021: CVE-2026-91021

> Attackers with note-authoring privileges can inject JavaScript into shared notes, executing code for other users including administrators.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 14 Sep 2026
- **Updated:** 14 Sep 2026
- **Also known as:** GHSA-g94c-cfqp-6xq2

## What is CVE-2026-91021?

CVE-2026-91021 is a medium-severity cross-site scripting vulnerability in Trilium Trillium Notes, published on 14 Sep 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

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.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-91021?


## How do I fix CVE-2026-91021?

No fix has been published for CVE-2026-91021 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-91021 being exploited?

There is no known exploitation of CVE-2026-91021 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-91021 and fix it if it is affected.

What it is: CVE-2026-91021 is a medium-severity cross-site scripting vulnerability in Trilium Trillium Notes, published on 14 Sep 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-91021 in the wild and no public exploit code.

Affected product: Trilium Trillium Notes. 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-2026-91021/ (Markdown: https://insights.sbomify.com/CVE-2026-91021/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91021
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91021
- OSV: https://osv.dev/vulnerability/CVE-2026-91021

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-91021/
Summaries are generated and may contain mistakes; the official description above is the record.