# CVE-2026-77170: Nextcloud Deck authorization bypass in config API

Source: https://junglewise.ai/threats/cve-2026-77170-nextcloud-deck-authorization-bypass-in-config-api  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-18. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-77170 · Severity: medium · CVSS 4.3 · Published 2026-09-18

Nextcloud Deck is a Kanban-style task and project management application used by organizations to organize work and collaborate on projects. An authenticated user can modify board configuration settings for any board in the system without authorization checks, potentially allowing them to alter another user's board settings, disrupt workflows, or access sensitive board data.

Vendors: [Nextcloud](https://junglewise.ai/threats/vendors/nextcloud).

## Quick answers

**Is CVE-2026-77170 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-77170 being exploited in the wild.

**How severe is CVE-2026-77170?** Medium severity, with a CVSS score of 4.3, published 18 September 2026.

**Which products and versions are affected?** Nextcloud Deck.

**Is there a fix for CVE-2026-77170?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-77170 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-77170?** Check whether you run Nextcloud Deck. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The Deck config API endpoint lacks proper authorization validation when setting board-scoped configuration keys. An authenticated attacker can specify arbitrary board IDs in API requests and modify configuration parameters without the system verifying the attacker's ownership or management permissions on the target board. The vulnerability requires authentication but allows an authenticated user to escalate privileges within the application by manipulating boards they do not own. Patches are expected from the Nextcloud security team.

## Affected products

- Nextcloud Deck

## Timeline

- 2026-09-18: disclosed
- other: CVE-2026-77170 assigned

## References

- [https://hackerone.com/reports/3599383](https://hackerone.com/reports/3599383)

## Related threats

- [Nextcloud Deck is a kanban style organization tool aimed at personal planning and project organization for teams integrated with Nextcloud.](https://junglewise.ai/threats/cve-2025-66548-nextcloud-deck-is-a-kanban-style-organization-tool-aimed-at)