XSS in Nextcloud Server
CVE-2021-32733
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.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.011 (62.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N.
Affected products
- Nextcloud Nextcloud_server
- Nextcloud Security-advisories — versions < 19.0.13, >= 20.0.0, < 20.0.11, >= 21.0.0, < 21.0.3
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (x_refsource_CONFIRM, Third Party Advisory)
- security-advisories@github.com (Patch, Third Party Advisory, x_refsource_MISC)
- security-advisories@github.com (Permissions Required, x_refsource_MISC)
Frequently asked questions
- What is CVE-2021-32733?
- CVE-2021-32733 is a medium-severity vulnerability in Nextcloud Server, classified under Cross-site Scripting. CVSS score: 4.8/10. Published 2021-07-12.
- How severe is CVE-2021-32733?
- Medium severity. CVSS v3 base score is 4.8 out of 10.
- Is CVE-2021-32733 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.