Auth bypass in Nextcloud Server
CVE-2021-41239
Nextcloud server is a self hosted system designed to provide cloud style services. In affected versions the User Status API did not consider the user enumeration settings by the administrator. This allowed a user to enumerate other users on the instance, even when user listings where disabled. It is recommended that the Nextcloud Server is upgraded to 20.0.14, 21.0.6 or 22.2.1. There are no known workarounds.
Vulnerability class: Information Disclosure
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.011 (65.1th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 65th percentile — 65.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: 0.000
Affected products
- Nextcloud Server — versions 22.2.0
- Nextcloud Security-Advisories — versions < 20.0.14, >= 21.0.0, < 21.0.6, >= 22.2.0, < 22.2.1
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/nextcloud/security-advisories/security/advisories/GHSA-g722-cm3h-8wrx (Third Party Advisory, Issue Tracking)
- github.com/nextcloud/server/issues/27122 (Patch, Third Party Advisory, Issue Tracking)
- github.com/nextcloud/server/pull/29260 (Patch, Third Party Advisory)
- security.gentoo.org/glsa/202208-17 (vendor-advisory, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-41239?
- CVE-2021-41239 is a medium-severity vulnerability in Nextcloud Server, classified under Information Disclosure. CVSS score: 5.3/10. Published 2022-03-08.
- How severe is CVE-2021-41239?
- Medium severity. CVSS v3 base score is 5.3 out of 10.
- Is CVE-2021-41239 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.