CVE-2026-125398 is a high-severity (CVSS 7.1) CWE-862 vulnerability in CoreBunch Instatic. A fix is available — see the affected versions and patch details below.
Instatic before 0.0.21 contains an authorization bypass vulnerability in handleRowAuthor that allows authenticated users to skip table-level access checks by loading rows with getDataRow()…
Description
Instatic before 0.0.21 contains an authorization bypass vulnerability in handleRowAuthor that allows authenticated users to skip table-level access checks by loading rows with getDataRow() instead of loadRowForAccess(). Attackers holding content.edit.any but lacking data.system.tables.read can send PATCH requests to /admin/api/cms/data/rows/:id/author to read system-table rows and reassign their authors.
Affected Products
InstaticCoreBunchDetection & mitigation playbook
Vendor / applianceDetect
Inventory every CoreBunch Instatic deployment and check each version against the affected-products list above.
Fix
Apply the CoreBunch Instatic security patch or hotfix for CVE-2026-125398 on the affected version, following the vendor advisory for your exact build.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
Frequently Asked Questions
Is CVE-2026-125398 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.