CVE-2021-41239
Published: 08 March 2022
Summary
CVE-2021-41239 is a medium-severity Exposure of Sensitive Information to an Unauthorized Actor (CWE-200) vulnerability in Nextcloud Nextcloud Server. Its CVSS base score is 5.3 (Medium).
Operationally, ranked in the top 40.7% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-28293
Vulnerability details
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…
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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.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Requiring attribute association with information prevents authorization from being performed without necessary security or privacy context.
Mandates authorization checks before permitting access or data processing via external systems.
The control provides a mechanism for authorized users to determine authorization matches, preventing sharing without proper authorization verification.
Session auditing enables detection of unauthorized exposure or access to sensitive information during user activities.
Sanitizing equipment to remove specified information before off-site maintenance prevents exposure of sensitive information to unauthorized actors such as external maintenance personnel.
Requiring detailed, requestable records of every PII disclosure directly aids detection of unauthorized exposures of sensitive information.
Ensures missing authorization mechanisms for critical data functions are identified and remediated via policy.
Annual reviews and proposal scrutiny detect and block matching programs that would expose sensitive data to unauthorized recipients or systems.