# CVE-2026-77167: Nextcloud federated share endpoint unauthenticated database write

Source: https://junglewise.ai/threats/cve-2026-77167-abusing-the-federated-share-endpoint-an-attacker-can-write  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-27. Updated: 2026-10-27  
License: CC BY 4.0 with a link back

CVE-2026-77167 · Severity: high · CVSS 7.5 · Published 2026-10-27

Nextcloud's federated sharing feature allows an unauthenticated attacker to inject arbitrary data into the database, creating persistent entries that never expire. This causes recurring denial-of-service conditions that renew automatically every 24 hours, potentially preventing legitimate users from accessing shared content and disrupting inter-instance federation.

Technologies: [Nextcloud Server](https://junglewise.ai/threats/technologies/nextcloud-server). Vendors: [Nextcloud](https://junglewise.ai/threats/vendors/nextcloud).

## Quick answers

**Is CVE-2026-77167 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-77167 being exploited in the wild.

**How severe is CVE-2026-77167?** High severity, with a CVSS score of 7.5, published 27 October 2026.

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

**Is there a fix for CVE-2026-77167?** 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-2026-77167 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-77167?** Check whether you run Nextcloud Server. 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

An unauthenticated attacker can abuse the federated share endpoint to write arbitrary rows into the oc_share_external database table. The injected rows persist indefinitely because the application lacks an automatic cleanup mechanism, allowing the attacker to trigger three distinct denial-of-service conditions that self-renew on a 24-hour cycle as long as the malicious entries remain in the database.

## Affected products

- Nextcloud Nextcloud Server

## Timeline

- 2026-10-27: disclosed

## References

- [https://hackerone.com/reports/3679640](https://hackerone.com/reports/3679640)

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