CVE-2021-43842 Stored XSS via SVG file upload in Wiki.js
A malicious user can execute arbitrary JavaScript in other users' browsers by uploading a crafted SVG file to Wiki.js.
- 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-2021-43842?
CVE-2021-43842 is a medium-severity cross-site scripting vulnerability in Requarks wiki, published on 20 Dec 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Wiki.js is a wiki app built on Node.js. Wiki.js versions 2.5.257 and earlier are vulnerable to stored cross-site scripting through a SVG file upload. By creating a crafted SVG file, a malicious Wiki.js user may stage a stored cross-site scripting attack. This allows the attacker to execute malicious JavaScript when the SVG is viewed directly by other users. Scripts do not execute when loaded inside a page via normal `<img>` tags. Commit 5d3e81496fba1f0fbd64eeb855f30f69a9040718 fixes this vulnerability by adding an optional (enabled by default) SVG sanitization step to all file uploads that match the SVG mime type. As a workaround, disable file upload for all non-trusted users. Wiki.js version 2.5.260 is the first production version to contain a patch. Version 2.5.258 is the first development build to contain a patch and is available only as a Docker image as requarks/wiki:canary-2.5.258.
Weakness: CWE-79
Which versions are affected by CVE-2021-43842?
It affects 1 product.
Products include Requarks Wiki.js.
How do I fix CVE-2021-43842?
No fix has been published for CVE-2021-43842 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-2021-43842 being exploited?
There is no known exploitation of CVE-2021-43842 in the wild and no public exploit code.
Other vulnerabilities in Requarks wiki
Sources
Also known as GHSA-3qv4-gp35-rgh7.