CVE-2021-43855

Public Exploit
Stored XSS via SVG in Requarks/wiki

Description

Wiki.js is a wiki app built on node.js. Wiki.js 2.5.263 and earlier is vulnerable to stored cross-site scripting through a SVG file upload made via a custom request with a fake MIME type. 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. The malicious SVG can only be uploaded by crafting a custom request to the server with a fake MIME type. A patch in version 2.5.264 fixes this vulnerability by adding an additional file extension verification check to the 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.

Category

8.2
CVSS
Severity: High
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.34%
Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory github.com
Affected: Requarks wiki
Published at:
Updated at:

References

Frequently Asked Questions

What is the severity of CVE-2021-43855?
CVE-2021-43855 has been scored as a high severity vulnerability.
How to fix CVE-2021-43855?
To fix CVE-2021-43855, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-43855 being actively exploited in the wild?
It is possible that CVE-2021-43855 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-43855?
CVE-2021-43855 affects Requarks wiki.
This platform uses data from the NIST NVD, MITRE CVE, MITRE CWE, First.org and CISA KEV but is not endorsed or certified by these entities. CVE is a registred trademark of the MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. CWE is a registred trademark of the MITRE Corporation and the authoritative source of CWE content is MITRE's CWE web site.
© 2025 Under My Watch. All Rights Reserved.