CVE-2026-121458 Details
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 Attackers can use the MCP interface to retrieve private or unpublished draft content and enumerate rows from the posts system table, resulting in cross-user data disclosure.
A missing authorization vulnerability has been identified in Instatic versions prior to 0.0.21. This vulnerability exists in the AI/MCP content read tools, where low-privileged authenticated users with 'ai.chat' and 'content.edit.own' capabilities can access data rows belonging to other users. The issue arises because the AI/MCP tools do not enforce the same object-level authorization checks as the normal HTTP API. As a result, attackers can use the MCP interface to retrieve private or unpublished draft content and enumerate rows from the posts system table, leading to unauthorized cross-user data disclosure.
Users can update to Instatic version 0.0.21 or later, where this vulnerability has been patched.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Nov 3, 2026CISA-ADP
Assessed Nov 3, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/CoreBunch/Instatic/releases/tag/v0.0.21 | [email protected] | Release NotesVendor |
| https://github.com/CoreBunch/Instatic/security/advisories/GHSA-x5cc-8486-8qqx | [email protected] | AdvisoryExploitRemedyVendor |
| https://www.vulncheck.com/advisories/instatic-before-authorization-bypass-via-mcp-content-read-tools | [email protected] | AdvisoryRemedy |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-862 | Missing Authorization | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| CoreBunch Instatic | >= 0.0.12, < 0.0.21 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Nov 3, 2026 | CVE Modified | CISA-ADP |
| Nov 3, 2026 | New CVE Received | [email protected] |