What’s Vulnerable › Vulnerabilities

CVE-2021-32733: XSS in Nextcloud Text application

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-07-12 · updated 2026-06-17
• Weakness: CWE-79

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.

Affected products

• Nextcloud Server: before 19.0.13; from 20.0.0 before 20.0.11; from 21.0.0 before 21.0.3 — fixed in 19.0.13, 20.0.11, 21.0.3

How to fix

Upgrade to a fixed version: Nextcloud Server 19.0.13, 20.0.11, 21.0.3. Check the vendor advisory for mitigations.

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

Get alerted when CVE-2021-32733 or the next vulnerability affects your stack