# CVE-2026-34212: Docmost page content has stored XSS via unsanitized attachment URLs

> A low-privileged user can inject malicious JavaScript via attachment URLs, allowing code execution in other users' browsers.

- **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 Apr 2026
- **Updated:** 15 Apr 2026
- **Also known as:** GHSA-cf68-cff9-hq4w

## What is CVE-2026-34212?

CVE-2026-34212 is a medium-severity cross-site scripting vulnerability in docmost, published on 14 Apr 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

Docmost is open-source collaborative wiki and documentation software. In versions prior to 0.71.0, improper neutralization of attachment URLs in Docmost allows a low-privileged authenticated user to store a malicious `javascript:` URL inside an attachment node in page content. When another user views the page and activates the attachment link/icon, attacker-controlled JavaScript executes in the context of the Docmost origin. Version 0.71.0 patches the issue.

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

## Which versions are affected by CVE-2026-34212?

It affects 1 product.


Products: Docmost Docmost.

## How do I fix CVE-2026-34212?

No fix has been published for CVE-2026-34212 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-34212 being exploited?

There is no known exploitation of CVE-2026-34212 in the wild and no public exploit code.

Public exploit code:

- Docmost accepted a javascript: URL inside an attachment node, preserved it through storage and rendering, and turned it back into a clickable anchor in the Docmost origin. (github_poc): https://github.com/0xmrma/CVE-2026-34212

## Other vulnerabilities in docmost

- [CVE-2026-24045](https://insights.sbomify.com/CVE-2026-24045/): Docmost Affected by Stored XSS in Public Share Page (high 7.3)
- [CVE-2026-22249](https://insights.sbomify.com/CVE-2026-22249/): Docmost affected by an Arbitrary File Write via Zip Import Feature (ZipSlip) (high 7.1)
- [CVE-2026-23630](https://insights.sbomify.com/CVE-2026-23630/): Docmost is vulnerable to stored Cross-Site Scripting (XSS) through Mermaid rendering (medium 6.3)
- [CVE-2025-55574](https://insights.sbomify.com/CVE-2025-55574/): Cross-site scripting in n/a (medium 6.1)
- [CVE-2026-40927](https://insights.sbomify.com/CVE-2026-40927/): Docmost: XSS in Comments with JavaScript URI (medium 5.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34212 and fix it if it is affected.

What it is: CVE-2026-34212 is a medium-severity cross-site scripting vulnerability in docmost, published on 14 Apr 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-2026-34212 in the wild and no public exploit code.

Affected product: docmost. 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-2026-34212/ (Markdown: https://insights.sbomify.com/CVE-2026-34212/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34212
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34212
- OSV: https://osv.dev/vulnerability/CVE-2026-34212

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34212/
Summaries are generated and may contain mistakes; the official description above is the record.