CVE-2026-121458

Instatic before 0.0.21 Authorization Bypass via MCP Content Read Tools

Published Nov 3, 2026 CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed
Description
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 Attackers can use the MCP interface to retrieve private or unpublished draft content and enumerate rows from the posts system table, resulting in cross-user data disclosure.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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 Attackers can use the MCP interface to retrieve private or unpublished draft content and enumerate rows from the posts system table, resulting in cross-user data disclosure.
Title Instatic before 0.0.21 Authorization Bypass via MCP Content Read Tools
First Time appeared Corebunch
Corebunch instatic
Weaknesses CWE-862
CPEs cpe:2.3:a:corebunch:instatic:*:*:*:*:*:*:*:*
Vendors & Products Corebunch
Corebunch instatic
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N'}

cvssV4_0

{'score': 7.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 8, 2026, 2:01 PM
Reserved
Nov 3, 2026, 12:47 PM
Status
Deferred
Published
Nov 3, 2026, 1:17 PM
Modified
Nov 3, 2026, 7:18 PM