---
id: CVE-2026-121458
title: Instatic before 0.0.21 Authorization Bypass via MCP Content Read Tools
summary: >-
  Instatic before 0.0.21 contains a missing authorization vulnerability in its
  AI/MCP content read tools that allows low-privileged authenticated users with
  ai.chat and content.edit.own capabilities to access data rows belonging to
  other u…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-862
vendor: CoreBunch
product: Instatic
affected:
  - Instatic >= 0.0.12 < 0.0.21
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-03T17:23:06.950734Z'
published: '2026-11-03'
updated: '2026-11-03'
sourceUpdated: '2026-11-03T18:31:26.636Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-121458'
references:
  - url: >-
      https://github.com/CoreBunch/Instatic/security/advisories/GHSA-x5cc-8486-8qqx
    label: Vendor Advisory
  - url: 'https://github.com/CoreBunch/Instatic/releases/tag/v0.0.21'
    label: Vendor Patch
  - url: >-
      https://www.vulncheck.com/advisories/instatic-before-authorization-bypass-via-mcp-content-read-tools
    label: >-
      VulnCheck Advisory: Instatic before 0.0.21 Authorization Bypass via MCP
      Content Read Tools
tags:
  - cve.org
epss: 0.00309
epssPercentile: 0.23856
ingestedAt: '2026-11-05T20:33:06.360Z'
---

## Overview

Instatic before 0.0.21 contains a missing authorization vulnerability in its AI/MCP content read tools that allows low-privileged authenticated users with ai.chat and content.edit.own capabilities to access data rows belonging to other users by calling content_get_document and content_list_documents without the object-level authorization checks enforced by the normal HTTP API. Attackers can use the MCP interface to retrieve private or unpublished draft content and enumerate rows from the posts system table, resulting in cross-user data disclosure.

## Affected

- `Instatic >= 0.0.12 < 0.0.21`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.