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

Medium 5.4 Published 14 Apr 2026 Updated 15 Apr 2026

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

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: None listed

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

Which versions are affected by CVE-2026-34212?

It affects 1 product.

Products include 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.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

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: 1 proofs of concept on GitHub.

Sources

Also known as GHSA-cf68-cff9-hq4w.