# CVE-2026-125398: Instatic before 0.0.21 Authorization Bypass via Row Author Reassignment Endpoint

Status: published. Published: 2026-11-09. Updated: 2026-11-09.

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.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/CoreBunch/Instatic/commit/ff1e51eb59c860864fa24e8c3e2716b56314f3ad

## Affected products and versions

- CoreBunch / Instatic: ≥ 0; < 0.0.21 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 7.1 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 7.1 (high); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-862

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/CoreBunch/Instatic/security/advisories/GHSA-m425-wmrc-4v4v (CNA: VulnCheck; vendor-advisory)

- https://github.com/CoreBunch/Instatic/commit/ff1e51eb59c860864fa24e8c3e2716b56314f3ad (CNA: VulnCheck; patch)

- https://github.com/CoreBunch/Instatic/releases/tag/v0.0.21 (CNA: VulnCheck; release-notes)

- https://github.com/CoreBunch/Instatic/blob/v0.0.20/server/handlers/cms/data/rows.ts#L378-L398 (CNA: VulnCheck; technical-description)

- https://www.vulncheck.com/advisories/instatic-before-0.0.21-authorization-bypass-via-row-author-reassignment-endpoint (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-125398; retrieved 2026-11-10; source updated 2026-11-09

Revision: 041e7747800dd703b6e4bb62e19d2ddc23ea84c862e078ee30e0c99f0f900482

Canonical: https://y2.dev/cve/CVE-2026-125398

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