Vulnerability Monitor

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CVE-2021-37630

Nextcloud Circles is an open source social network built for the nextcloud ecosystem. In affected versions the Nextcloud Circles application allowed any user to join any "Secret Circle" without approval by the Circle owner leaking private information. It is recommended that Nextcloud Circles is upgraded to 0.19.15, 0.20.11 or 0.21.4. There are no workarounds for this issue.

Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 6.5, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction requiring only low-level privileges . The vulnerability impacts confidentiality (data exposure), for affected systems. Impacting 1 product from nextcloud organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.

Published

2021-09-07T20:15:07.847

Last Modified

2024-11-21T06:15:33.660

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 6.5 (MEDIUM)

CVSSv2 Vector

AV:N/AC:L/Au:S/C:P/I:N/A:N

Access Vector: NETWORK
Access Complexity: LOW
Authentication: SINGLE
Confidentiality Impact: PARTIAL
Integrity Impact: NONE
Availability Impact: NONE

Exploitability Score

8.0

Impact Score

2.9

Weaknesses

Type: Secondary
CWE-639
Type: Primary
CWE-639

Affected Vendors & Products

Type	Vendor	Product	Version/Range	Vulnerable?
Application	nextcloud	circles	< 0.19.5	Yes
Application	nextcloud	circles	< 0.20.11	Yes
Application	nextcloud	circles	< 0.21.4	Yes

References

https://github.com/nextcloud/circles/pull/768 Patch, Third Party Advisory ([email protected])
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-56j9-3rj4-wvgm Third Party Advisory ([email protected])
https://hackerone.com/reports/1257624 Permissions Required, Third Party Advisory ([email protected])
https://github.com/nextcloud/circles/pull/768 Patch, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-56j9-3rj4-wvgm Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://hackerone.com/reports/1257624 Permissions Required, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For nextcloud's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.