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Advisory record · GHSA-8vh3-g2qg-2h2c

nextcloud-mcp-server: Unauthenticated `POST /webhooks/nextcloud` allows arbitrary vector data deletion when `WEBHOOK_SECRET` is unset ( default )

CVSS 9.1 CriticalCriticalEPSS 0.0073 · 54th percentile

Critical, because:

  • CVSS score 9.1: 9.0 or more.

How we decide what’s critical

Published by the GitHub Advisory Database at 25 Aug 2026, 16:04 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
nextcloud-mcp-serverPyPI<0.117.20.117.2
Identifiers
GHSA-8vh3-g2qg-2h2c · CVE-2026-55640 · PYSEC-2026-3866
Weakness (CWE)
CWE-306
Tags
Published
25 Aug 2026
Updated
10 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

The nextcloud-mcp-server package before 0.117.2 exposes an unauthenticated POST /webhooks/nextcloud endpoint when WEBHOOK_SECRET is unset, which is the default. A remote attacker with network access to the service can send forged payloads that set any user's ID, causing deletion or corruption of that user's vector embeddings in Qdrant. Upgrade to nextcloud-mcp-server 0.117.2 or later; setting WEBHOOK_SECRET to a value also requires the webhook to be authenticated.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
9.1 Critical 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0073, the 54th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:10 UTC First seen by agentprime
  2. 31 Oct 2026, 14:10 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.