CVE-2021-43856

Public Exploit
Stored XSS in non-image uploads 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 non-image file uploads for file types that can be viewed directly inline in the browser. By creating a malicious file which can execute inline JS when viewed in the browser (e.g. XML files), a malicious Wiki.js user may stage a stored cross-site scripting attack. This allows the attacker to execute malicious JavaScript when the file is viewed directly by other users. The file must be opened directly by the user and will not trigger directly in a normal Wiki.js page. A patch in version 2.5.264 fixes this vulnerability by adding an optional (enabled by default) force download flag to all non-image file types, preventing the file from being viewed inline in the browser. As a workaround, disable file upload for all non-trusted users. --- Thanks to @Haxatron for reporting this vulnerability. Initially reported via https://huntr.dev/bounties/266bff09-00d9-43ca-a4bb-bb540642811f/

Category

8.2
CVSS
Severity: High
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.40%
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-2021-43856?
CVE-2021-43856 has been scored as a high severity vulnerability.
How to fix CVE-2021-43856?
To fix CVE-2021-43856, 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-2021-43856 being actively exploited in the wild?
It is possible that CVE-2021-43856 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-2021-43856?
CVE-2021-43856 affects Requarks wiki.
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