CVE-2026-121458

Medium

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 Attackers can use the MCP interface to retrieve private or unpublished draft content and enumerate rows from the posts system table, resulting in cross-user data disclosure.

SeverityMedium

CVSS6.5

Exploit probability—

ProductInstatic

PublishedNov 3, 2026

First seenNov 4, 2026

Weakness typeCWE-862Missing authorization

How to fix

Update

CoreBunch Instatic0.0.21 or later

Patches

github.com/CoreBunch/Instatic/releases/tag/v0.0.21

Vendor advisories

github.com/CoreBunch/Instatic/security/advisories/GHSA-x5cc-8486-8qqx

Affected products

Product	Affected versions	Fixed in
CoreBunch Instatic	0.0.12 ≤ v < 0.0.21	0.0.21

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